๐Chemistry
Short Questions
- i. Why is there a need to divide Chemistry into many branches? Give three reasons.
- ii. Reactions may take place due to electrons present outside the nucleus or they may take place inside the nucleus. Which branches of Chemistry cover these two types of reactions?
- iii. What types of problems are solved in analytical chemistry?
- iv. Both graphite and graphene have hexagonal layered structures. What is the difference?
- v. Why are supercritical fluids important?
- vi. In which state does matter exist in the Sun?
- vii. What is the importance of graphene?
- viii. Which form of matter do most of the material things in this world belong to?
- Why is it said that almost all the mass of an atom is concentrated in its nucleus?
- Why are elements different from one another?
- How many neutrons are present in \( ^{210}_{68} \text{Bi} \)?
- Why is tritium (\( ^{3}_{1} \text{H} \)) a radioactive element?
- How can an atom absorb and envolve energy?
- What type of elements lose their outer electron easily and what type of elements gain electron easily?
- Why do lower molecular mass covalent compounds exist as gases or low boiling liquids?
- Give one example of an element which exists as a crystalline solid and it has covalent bonds between its atoms.
- Which property of metals makes them malleable and ductile?
- Is coordinate covalent bond a strong bond?
- Write down dot and cross formula of HNO₃.
- Write down the chemical formula of barium nitride.
- Find out the molecular formula of a compound whose empirical formula is CH₂O and its molar mass is 180.
- How many molecules are present in 1.5 g H₂O?
- What is the difference between a mole and Avogadro's number?
- Write down the chemical equation of the following reaction. Copper + Sulphuric acid → Copper sulphate + Sulphur dioxide + Water
- What is the difference between enthalpy and enthalpy change?
- Why is breaking of a bond an endothermic process?
- Depict the transition state for the following reaction. \[ H_2 + Cl_2 \rightarrow 2HCl \]
- Draw the reaction profiles for two exothermic reactions one of which moves faster than the other.
- What is the role of glycogen in our body?
- How is dynamic equilibrium different from the static equilibrium?
- How the following reversible reaction will be affected if its temperature is increased? \[2H_2O_{61} \xrightarrow{\text{Electricity}} 2H_{369} + O_{249}\]
- How can you get the maximum yield in a reversible reaction?
- How can you decrease the time to attain the position of equilibrium in a reversible reaction?
- What is the effect of increasing pressure on the following reaction at equilibrium? \[N_{349} + O_{249} \xrightarrow{\text{2NO}_{45}}\]
- Choose Arrhenius Acids among the following compounds. HF, \( \text{NH}_4 \), \( \text{H}_2\text{SO}_3 \), \( \text{SO}_2 \), \( \text{H}_2\text{S} \), \( \text{H}_2\text{O} \)
- How does calcium metal react with dilute \( \text{H}_2\text{SO}_4 \)?
- Which salts formed when HCl reacts with \( \text{BaCO}_3 \)?
- How will you justify that \( \text{HSO}_4^- \) is a Bronsted – Lowry acid?
- Why is HCl not edible although it is present in the stomach and responsible for digestion of food?
- Why was atomic number chosen to arrange the elements in the periodic table?
- What is the significance of the word periodic?
- Why does the size of a period increase as we move down the periodic table?
- In a group, the elements have the same number of electrons in the outermost shell. Why is it so?
- Do you expect calcium to be more reactive than sodium? Give the reason of your answer.
- Which element has the maximum atomic radius and which element has the minimum atomic radius in third period?
- Why are the most electronegative elements present in sixth and seventh groups?
- The first ionization energy value of magnesium is less than the second one. Give reason.
- Is it possible for two metals or two non-metals to form an ionic bond?
- Which element has the least value of ionization energy and which element has the highest value of electronegativity?
- Why does it become easier to cut an alkali metal when we move from top to bottom in a group?
- Predict the reactivity of potassium towards halogens.
- In the following reaction, chlorine acts as an oxidising agent. Which is the reducing agent? \[ \text{Cl}_{2(g)} + 2\text{NaBr}_{(aq)} \rightarrow 2\text{NaCl}_{(aq)} + \text{Br}_{2(l)} \]
- Why does iodine exist in the solid state at room temperature?
- How does Ni catalyse the reaction involving hydrogenation of oil?
- What is the main objective of environmental education?
- How is particulate matter released in the atmosphere?
- Which gas is more poisonous, CO or CO₂?
- How does acid rain affect forests?
- In what way sulphur present in fossil fuels becomes dangerous?
- Name any three major sources responsible for the greenhouse effect.
- How is wind energy useful for us?
- Differentiate between an organic and an inorganic compound.
- Why are organic compounds found in large numbers?
- Name the products which are obtained when natural gas is oxidized under controlled conditions.
- How naphtha fraction is decomposed to give lower hydrocarbons?
- Write down the molecular formula, structural formula and the condensed structural formula for iso-butane.
- How are organic compounds useful for us?
- Write down the names of five such organic compounds which exist naturally?
- Give IUPAC name to the following compound: \[ \text{CH}_3 - \text{CH} - \text{CH}_2 - \text{CH}_3 \]
- How do the melting and boiling points of alkanes change when we move from lower members to higher members?
- What is consistency of results?
- Why SI units are user friendly?
- Define systematic error and random error.
- What is reason behind a random error?
- Does systematic error affect the accuracy?
- Which other systems of measurements are used apart from SI units?
- Define metre.
- Mention two benefits scientists get by using SI units.
- Name some corrosive chemicals.
- What type of safety precautions are adopted to avoid damage due to explosive chemicals?
- What type of damages can reactive chemicals cause?
- Indicate two such safety instructions which are required to avoid radiation.
- Which chemicals can cause suffocation?
- Why signs and symbols are posted on lab, and chemical bottles?
- How fire caused by chemicals should be handled?
- Why emergency drills are important to face emergency situations?
CHAPTER 1
CHAPTER 2
CHAPTER 3
CHAPTER 4
CHAPTER 5
CHAPTER 6
CHAPTER 7
CHAPTER 8
CHAPTER 9
CHAPTER 10
CHAPTER 11
CHAPTER 12
CHAPTER 13
Long Questions
- How does a supercritical state look like?
- In what way is plasma created in a fluorescent tube?
- Most of the molecules we study in biochemistry are organic in nature. Where does the difference exist in organic and biochemistry branches of Chemistry?
- Give the reason of brilliance shown by diamond. Can you improve it?
- Explain the dissolution of sodium chloride in water.
- Why do different compounds have different solubilities in water at a particular temperature?
- Why NaCl can not be crystallized from water just like KNO₃?
- Why graphite is slippery to touch? Which property of graphite enables it to be used as lubricant?
- Mention the name of the branch of Chemistry in which you will study each of the following topics: (a) Rate of a reaction (b) Digestion of food in human body (c) Properties of plasma (d) Ecosystem (e) Reactions taking place during fireworks (f) Measurement of the absorption of wavelength with the help of ultraviolet spectrometer
- What are allotropic forms? Explain the allotropic forms of carbon and sulphur. How does coal differ from diamond?
- What are supercritical fluids. How are they different from ordinary liquids?
- Define solubility of a solute. How does the solubility of solutes change with the increase in temperature?
- What types of movements are present in gaseous and liquid molecules?
- Differentiate between the areas which are studied under inorganic and organic chemistry.
- Why does the energy of electron increase as we move from first shell to second shell?
- Why is it needed to lower the pressure of the gas inside the discharge tube?
- What is the classical concept of an electron? How has this concept changed with time?
- Why the nuclei of the radioactive elements are unstable?
- During discharge tube experiments, how did the scientists conclude that the same type of electrons and protons are present in all the elements?
- Explain the structure of a hydrogen atom.
- How does the theory of atomic structure explain the ionization of atoms by a radioactive isotope?
- What is radioactivity? Explain any three applications of radioactive isotopes.
- Find out the relative atomic mass of mercury from the following data.
- Why HF is a liquid while HCl is a gas?
- Why covalent compounds are generally not soluble in water?
- How do metals conduct heat?
- How many oxides does nitrogen form. Write down the formulae of oxides?
- What will happen if NaBr is treated with AgNO₃ in water?
- Why does iodine exist as a solid while Cl₂ exist as a gas?
- Explain the formation of an ionic bond and a covalent bond.
- How do ions arrange themselves to form NaCl crystal.
- Explain the properties of metals keeping in view the nature of metallic bond.
- Compare the properties of ionic and covalent compounds.
- How will you explain the electrical conductivity of graphite crystals?
- Why are metals usually hard and heavy?
- Different compounds will never have the same molecular formula but they can have the same empirical formula. Explain
- Write down the chemical formulas of the following compounds. Calcium phosphate, Aluminium nitride, Sodium acetate, Ammonium carbonate and Bismuth sulphate.
- Why does Avogadro's number have an immense importance in chemistry?
- When 8.657g of a compound were converted into elements, it gave 5.217g of carbon, 0.986g of hydrogen and 2.478g of oxygen. Calculate the percentage of each element present in this compound.
- How can you calculate the masses of the products formed in a reversible reaction?
- Which conditions must be fulfilled before writing a chemical equation for a reaction?
- Explain the concepts of Avogadro's number and mole.
- How many grams of CO₂ will be produced when we react 10 g of CH₄ with excess O₂ according to the following equation?
- How many moles of coal are needed to produce 10 moles of CO according to the following equation?
- How much SO₂ is needed in grams to produce 10 moles of sulphur according to the following equation?
- How much ammonia is needed in grams to produce 1 kg of iron fertilizer according to the following equation?
- Calculate the number of atoms in the following. (a) 3g of H₂ (b) 3.4 moles of N₂ (c) 10g of C₆H₁₂O₆
- Explain why the reaction between atmospheric gases oxygen and nitrogen does not take place under normal conditions? But in the presence of lightning these gases react to give NO. The reaction stops as soon as the lightning stops.
- A reaction between natural gas (CH₄) and atmospheric oxygen does not take place when you mix them. As soon as you show a burning match stick, the reaction starts immediately and then it continues until one or both of the reactants is/are used up. Explain.
- Find out the enthalpy change of the following reaction using the given data. \[N_2 + O_2 \rightarrow 2NO\] Bond dissociation energy of \( N_2 = 958.38 \, \text{kJ/mol} \) Bond dissociation energy of \( O_2 = 498 \, \text{kJ/mol} \) Bond formation energy of \( NO = 626 \, \text{kJ/mol} \)
- Explain the difference between the terms heat and enthalpy.
- Explain why formation of a bond is always an exothermic process.
- Explain the role of lipids in our body.
- Explain the following terms. Activation energy, Transition state, Aerobic respiration
- Why are some reactions irreversible while others are reversible?
- Why are combustion reactions generally irreversible?
- Can you make an irreversible reaction reversible and vice versa?
- How do you know if a reaction is reversible or irreversible?
- Do the phase changes in water (solid to liquid, liquid to vapour) reversible or irreversible?
- How can you drive the reversible reaction at equilibrium? (a) in the forward direction (b) in the backward direction
- Explain how the rates of forward and backward reactions change when the system approaches equilibrium.
- Describe the effect of a catalyst on the reversible reaction.
- How can a reversible reaction be forced to go to completion?
- How does change in temperature affect the reaction at equilibrium?
- What chemical name will you give to soap as a compound?
- In the presence of a drop of an acid, water is known to ionize as follows: \[ \text{H}_2\text{O} \xrightarrow{\text{H}^+_{\text{acid}}} \text{OH}^- \] In your opinion, which name will be suitable for water: an acid, a base or both?
- Why does Na₂CO₃ behave like a base in water?
- Is NaHCO₃ a base or an acid? Justify your answer.
- What is the difference between a strong acid and a concentrated acid?
- Explain Arrhenius concept of acids and bases.
- Compare Arrhenius and Bronsted – Lowry concepts of acids and bases.
- How does sulphuric acid react with the following compounds? NH₄Cl, NH₄NO₃, MgO, MgCO₃
- What happens when a base reacts with a non-metallic oxide. What do you infer about the nature of non-metallic oxide?
- State the reason of showing acidic character by both dry HCl gas and HCl solution in water.
- Differentiate between an acid and its conjugate base.
- Suppose a new element is discovered. Where would you like to accommodate this element in the periodic table?
- What is the first element of the periodic table? Will it lose an electron or gain it?
- Atomic radii of boron and aluminum are 88 pm and 125 pm respectively. Which element is expected to lose electron or electrons easily?
- How would you find the atomic radius of an atom?
- Why is it not possible for oxygen atom to accept three electrons to form O³⁻ ion like nitrogen which can accept electrons to form N³⁻?
- Which information is needed to locate the elements in the periodic table if you do not know its atomic number? Is atomic mass helpful for this purpose?
- How many blocks of elements are present in the periodic table? Are these blocks helpful in studying the properties of elements?
- Explain the variation in the following properties in the periods giving reasons. (a) Atomic radius (b) Ionization energy
- Which physical properties of elements may lead us to know what type of bond it will form?
- Write down the names of four non-metals which exist in solid state at normal temperature.
- Why do second and third periods have equal number of elements while all other periods contain different number of elements?
- Which noble gas should have the lowest boiling point and why?
- Compare the reactions of alkali metals with chlorine.
- Why are almost all the metals solids while non-metals generally exist as gases and solids?
- Name any three elements in the periodic table which exists as liquids.
- Why are transition elements different from normal elements?
- Compare the reactivity of chlorine and bromine as an oxidising agent.
- Which element is the most reactive and which is the least reactive among halogens? Give two reasons to explain your answer.
- Explain the role of catalytic converter in an automobile.
- Why do the chemical reactivities of alkali metals increase down the group whereas they decrease down the group in case of halogens?
- Why are metals generally tough and strong whereas non-metals are neither tough nor strong?
- Both alkali metals and halogens are very reactive elements with roles opposite to each other. Explain.
- Why hydrogen bromide is thermally unstable as compared to hydrogen chloride?
- Compare the properties of metals and non-metals.
- V₂O₅ catalyst is preferred over platinum in the oxidation of sulphur dioxide. Give reasons.
- How is the excessive use of insecticides and pesticides harmful for birds?
- Percentage of CO₂ in air is only 0.04%. Then how does it become harmful for the ecosystem?
- Why only some pollutant gases present in the atmosphere cause green house effect while others do not?
- How can you reduce the emission of CO present in the gases emitted by the burning of fuel in the automobile engines?
- Mention three different ways in which solar energy can be useful for us.
- Describe the harmful effects of the major pollutants present in the air.
- Explain greenhouse effect. How is global warming dangerous for us?
- What is air quality index? What information does it convey?
- Who are high risk groups and why is pollution more dangerous for them?
- Describe three strategies to address environmental issues.
- Why do alkanes show little reactivity towards the other reagents?
- Why does a mixture of natural gas and air explode?
- How do you compare the melting and boiling points of inorganic and organic compounds?
- Reactions of alkanes with chlorine takes place in the presence of sunlight. What is the role of sunlight in the reaction?
- How do you compare the boiling point of n – butane with that of iso – butane?
- Why are organic compounds not generally soluble in water?
- Describe the importance of organic compounds in daily life.
- Why is carbon so important as an element that the whole branch of chemistry is based on it?
- A carbon–carbon single bond (C – C) in alkanes does not behave as a functional group but a carbon carbon double bond (C = C) in alkenes does. Explain.
- Explain IUPAC system of nomenclature for alkanes.
- How combustion reaction of alkanes is useful for us?
- Compare the units in SI system with those in MKS system?
- What are five basic SI units which are used in Chemistry?
- Explain the three units derived for the basic SI units.
- Explain why do we prefer to use smaller units of mass and volume in Chemistry?
- What difficulties we expect to encounter if we use different units of measurement in daily life.
- What are our indigenous units of measurement of mass, volume and length?
- Elaborate the difference between precision and accuracy.
- How can you avoid systematic errors in your measurements?
- How do taking measurements in SI units ensure safety and reliability?
- Can a student be both inaccurate and imprecise in his measurements?
- How will you handle an emergency situation caused by fire due to short circuiting?
- What type of reactions should be carried out in fume cupboard?
- Put forward at least two suggestions to improve safety in the lab.
- Can you identify warning symbols posted for radiation and asphyxiant chemicals?
- Why sudden shock can cause some chemicals to explode?
- Explain hazards due to explosive and toxic chemicals.
- Write down five such common safety instructions which are used to avoid all types of hazards.
- Explain the importance of warning signs and symbols to avoid any accident in the lab.
- Name some toxic chemicals. Describe the effects of spreading toxic gas in the lab.
- A student has spilled over a corrosive and explosive chemical due to an accident. Which emergency measures you will take to tackle the situation.
CHAPTER 1
CHAPTER 2
CHAPTER 3
CHAPTER 4
CHAPTER 5
CHAPTER 6
CHAPTER 7
CHAPTER 8
CHAPTER 9
CHAPTER 10
CHAPTER 11
CHAPTER 12
CHAPTER 13
Administrator: SADIA ANWAR Assistant: KHADIJA AHMED
Time Allowed: ?
Total Marks: ?
Syllabus: ?
Institute: ?
INSTRUCTONS
*Note: Write answers neatly and in sequence.Use black or blue pen only.
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