Question

I. Give one word answer for the following:(1*6=6)

i) The type of change during which heat is absorbed-

ii) An example of a triatomic molecule-

iii) The device used to separate a mixture of oil and water-

iv) The first person to propose that matter is made up of ‘Parmanu’-

v) The Latin name of Mercury –

vi)The gas that is liberated when Copper carbonate is heated-

II) Write True or False. Also correct the wrong statements, if any:(1*5=5)

i) Copper salts are mostly white in colour –

ii) Niels Bohr was the first person to give the idea of electron shells-

iii) The chemical symbol of Bromine is B-

iv) Compounds can be broken down by physical methods-

v) Solids have high densities-

III) Find the odd one out. Also give reasons for your answer: (2*5=10)

i) Element, Proton, Neutron, Electron –

ii) Nitrogen, Oxygen, Gold, Hydrogen-

iii) Camphor, Iodine, Naphthalene, Calcium-

iv) Freezing of water, drying of clothes, Cooking of food, Glowing of electric bulb-

v) Idli, Boiled rice, hard drinks, Talcum powder-

IV) Complete the following table:(3*3=9)

Element/Ion Protons Electrons Neutrons

i) 64 Cu

29

ii) 23 Na



11SECTION-B (40 marks)

A. Answer the following questions: (10*4 = 40)

I. i) Give three points of difference between physical and chemical change. (3)

ii) Write a short note on Fraction Distillation. (3)

iii) What do you observe when an iron rod is immersed in Copper sulphate solution? Give

equation to support your answer.(4)

II) i) Write any three properties of compounds. (3)

ii) Mention three important points of Dalton’s atomic theory. (3)

iii) Balance the following chemical equations: (1*4=4)

a) NaNO3 NaNO2 + O2

b) Mg + HNO3 Mg(NO3)2 + H2

c) Na + H2O NaOH + H2

d) P + O2 P2O5

III) i) What is the significance of the formula of a substance? (3)

ii) Define – a) Radicals b) Valency (1.5*2=3)

iii) Write the chemical formula of the following: (1*4=4)

a) Aluminium sulphate

b) Copper chloride

c) Ammonium Sulphate

d) Zinc Carbonate

IV) i) Write short notes on – a) Decomposition reaction and, b) Simple displacement

reactions, with the help of examples. (3)

ii) Give any three characteristics of elements. (3)

iii) Draw the electronic configuration of the following: (1*4=4)

a) Chlorine b) Aluminium c) Sulphur d) Calcium​

Answer 1

Answer:

Explanation:

The significance of a chemical equation is as

follows:

(i) Chemical equation describes briefly the names of

the reactants, the products and the state of matter.

(ii) It explains the specific conditions of temperature,

pressure, catalyst, etc. under which the reaction

takes place.

(iii) It also states whether energy is evolved or needs

to be supplied.

(iv) Chemical equation also represents the relative

number of molecules and moles of reactants and

products.

(v) The relative masses of the reactants and products

can also be calculated using a chemical equation.

Thus, a chemical equation describes a chemical

reaction qualitatively as well as quantitatively.

Answer 2

Answer:

Explanation:

The significance of a chemical equation is as

follows:

(i) Chemical equation describes briefly the names of

the reactants, the products and the state of matter.

(ii) It explains the specific conditions of temperature,

pressure, catalyst, etc. under which the reaction

takes place.

(iii) It also states whether energy is evolved or needs

to be supplied.

(iv) Chemical equation also represents the relative

number of molecules and moles of reactants and

products.

(v) The relative masses of the reactants and products

can also be calculated using a chemical equation.

Thus, a chemical equation describes a chemical

reaction qualitatively as well as quantitatively.