Carbon and its Compounds — Science STD 10 — Question

Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it, as shown in figure below.

1. What will be the action of gas on:

1. Dry litmus paper?
2. Moist litmus paper?

2. Write a balanced chemical equation for the reaction taking place.

Samples of four metals A, B, C and D were taken and added to the following solution one by one. The results obtained have been tabulated as follows.

Metal	Iron (II) sulphate	Copper (II)sulphate	Zincsulphate	Silver nitrate
A	No reaction	Displacement	-----	-----
B	Displacement	-----	No reaction	-----
C	No reaction	No reaction	No reaction	Displacement
D	No reaction	No reaction	No reaction	No reaction

Use the Table above to answer the following questions about metals A, B, C and D.

1. Which is the most reactive metal?
2. What would you observe if B is added to a solution of Copper(II) sulphate?
3. Arrange the metals A, B, C and D in the order of decreasing reactivity.

Explain the following terms with one example each:

1. Corrosion.
2. Rancidity.

2mL of sodium hydroxide solution is added to a few pieces of granulated zinc metal taken in a test tube. When the contents are warmed, a gas evolves which is bubbled through a soap solution before testing. Write the equation of the chemical reaction involved and the test to detect the gas. Name the gas which will be evolved when the same metal reacts with dilute solution of a strong acid.

The atomic number of an element is 19.

1. Write the electronic configuration of this element and determine (i) the valency of this element, and (ii) whether this element is a metal or a non-metal.
2. Write the formula of the oxide of this element.
3. Is this element more reactive or less reactive than Na (atomic number 11)? Justify your answer giving example.

A hard material X which is mined from the earth is used as a house hold fuel and also for the generation of electricity at Thermal Power Stations. A soft material Y is also used us a fuel in the form of candles. A gaseous material Z which occurs along with petroleum is increasingly being used as a fuel in running vehicles in its compressed form.

1. What are materials, X, Y and Z?
2. When materials X, Y and Z are burned separately:

1. When material burns by producing a yellow, luminous flame?
2. Which material ultimately burns without producing a flame?
3. Which material can burn in a gas stove by producing a blue flame?

The atomic masses of three elements X, Y and Z having similar chemical properties are 7, 23 and 39 respectively.

1. Calculate the average atomic mass of elements X and Z.
2. How does the average atomic mass of elements X and Z compare with the atomic mass of element Y?
3. Which law of classification of elements is illustrated by this example?
4. What could the elements X, Y and Z be?
5. Give another example of a set of elements which can be classified according to this law.

State one characteristic each of the chemical reaction which takes place when:
i. Dilute hydrochloric acid is added to sodium carbonate.
ii. Lemon juice is added gradually to potassium permanganate solution.
iii. Dilute sulphuric acid is added to the barium chloride solution.
iv. Quick lime is treated with water.
v. Wax is burned in the form of a candle.

What is meant by denatured alcohol? What is the need to denature alcohol?

1. Name a metal for each case:

1. It does not react with cold as well as hot water but reacts with steam.
2. It does not react with any physical state of water?

2. When calcium metal is added to water, the gas evolved does not catch fire but the same gas evolved on adding sodium metal to water catches fire. Why is it so?