Chemistry
Class:- VII
Language of chemistry
Q.1 Write the symbols of the following elements
1) Zinc
2) Phosphorus
3) Manganese
4) Nickel
5) Potassium
6) Calcium
7) Calcium
8) Lead
9) Gold
10) Neon
Q.2 Find the valencies of the underlined element
1) BaCl2
2) FeO
3) Fe2O3
4) CaCO3
5) Na2O
6) Al(OH)3
7) SO2
8) NH3
Q.3 Define.
1) Valency
2) Molecule
3) Formula
4) Compound
5) radical
6) Symbol
7) Balanced chemical equation
Q.4 Write the formula of the following compounds
1) Nitric acid
2) Potassium carbonate
3) Ammonia
4) Calcium dioxide
5) Sodium hydroxide
6) Carbon monoxide
7) Hydrogen chloride
8) Sulphuric acid
Q.5 Give examples each of the following.
1) Binary compound
2) Trivalent
3) Monovalent
4) Triatomic gas
5) Divalent
6) Noble gas
7) Diatomic gas
Q.6 Write the valency/valencies of the following
1) Hydrogen 5) Iron
2) Carbon 6) Copper
3) Nitrogen 7) Sulphur
4) Phosphorus 8) Lead
Q.7 Balance the chemical equation
1) Mg + O2 → MgO
2) N2 + O2 → NO
3) CH4 + O2→ CO2 + H2O
4) NO2 + H2O → NO + HNO3
Q.8 Match the following.
A B
1) Potassium a) Aurum
2) Iron b) Stannum
3) Silver c)Ferrum
4) Gold d)Argentum
5) Tin e) Kalium
Q.9 Represent the addition of dilute sulphuric acid to zinc by means of a chemical
equation. State the function of the arrow between the reactants and products.
Q.10 Give a balanced equation for addition of iron to copper [II] sulphate solution. State the
change in colour seen.
Q.11
In certain reactions an insoluble solid called precipitate is formed. State the colour and
name of the precipitate formed in each of the following reactions involving addition of:
(a) Dilute hydrochloric acid to silver nitrate
(b) Iron [II] sulphate to sodium hydroxide
(c) Iron [III] chloride to ammonium hydroxide
(d) Copper [II] sulphate to sodium hydroxide
(e) Lead nitrate to ammonium hydroxide
Q 12. Select the correct answer from A, B, C, D and E for each statement given below:
A: Hydrogen
B: Copper [II] oxide
C: Oxygen
D: Copper [II] hydroxide
E: Ammonia
The black residue obtained on heating copper carbonate.
The basic gas obtained when two gases react in presence of a catalyst and the reaction is
exothermic.
The gas obtained when potassium chlorate is heated in the presence of a catalyst.
The pale blue precipitate obtained when copper [II] sulphate reacts with sodium hydroxide.
The gas which reacts with oxygen to give a neutral liquid.
Q.13 Give reasons for the following:
1. Even though rusting is an exothermic reaction, the heat evolved when an iron
nail rusts are unnoticeable.
2. Electrolytic decomposition of water is a reaction involving a change of state.
3. A characteristic change of colour is seen when a piece of iron is added to
copper [II] sulphate solution.
4. The catalytic oxidation of sulphur dioxide to sulphur trioxide is represented
by a double arrow [⇌] between reactants and products, formed in the
chemical reaction.
5. Silver salts are kept in dark coloured bottles.
