Question

Question Paper
Standard X Chemistry Chemical Reactions and Equations Subj...

1

In electrolysis of water, why is the volume of gas collected over one electrode double than that of gas collected over the other electrode? [1 MARK]

Explanation: 1 Mark

In water (
H
2
O
), hydrogen and oxygen are present in the ratio of 2:1 by volume, and thus the volume of hydrogen gas collected is double that of oxygen gas.

2

How can you help your mother in keeping the fried items so that they do not develop a foul smell and their shelf life is increased? [2 MARKS]
Each point: 1 Mark

1. Since we cannot pack the fried objects in the atmosphere of nitrogen at home, we can increase their shelf life by keeping them in airtight containers.

2. In this way, they do not come in contact with oxygen. Their shelf life can further be increased by refrigerating at low temperatures.

3

A solution of a substance 'X' is used for white washing.
1. Name the substance 'X' and write its formula.
2. Write the reaction of the substance 'X' named in (i) above with water.[2 MARKS]
Each point: 1 Mark

1. The substance 'X' is calcium oxide (quick lime). Its formula is
CaO
.

2.
CaO(s)
+
H
2
O(l)
→
Ca(OH)
2
(aq)

4

Define a combination reaction. Give one example of a combination reaction which is also exothermic. [2 MARKS]
Each point: 1 Mark

1. Reactions in which two or more substances combine to form a new compound are called combination reactions.
2. Example- combustion of magnesium in air, where magnesium combines with oxygen to form magnesium oxide.​

Answer 1

Answer:

Tq very much ...........

Answer 2

Answer:

that you very much for your help