Question

Q4) Raman uses solution of a substance X for white washing his house. Name the substance X.
ਰਮਨ ਕਿਸੇ
ਵਸਤੂ
X ਦੇ ਘੋਲ ਦੀ ਵਰਤੋਂ ਸਫੈਦੀ ਕਰਨ ਲਈ ਵਰਤਦਾ ਹੈ। ਵਸਤੂ ‘X' ਦਾ ਨਾਮ ਦੱਸੋ |
A) CaO
B) CaCO3
C) NaCl
D) Cuo
Q5) Teacher wrote the electronic configuration of an atom of an element as ? 8 7 What ir tt​

Answer 1

Ans. 4

A) CaO

$\rule{100}2$

Explanation

The substance used for white washing is CaO (Calcium Oxide). Therefore, the substance X is Calcium oxide having formula CaO.

When Calcium oxide reacts with water, following reaction takes place-

$\sf{CaO+H_2O\rightarrow Ca(OH)_2}$

When Calcium oxide reacts with water formation of Calcium Hydroxide (another name - Slaked lime) having formula Ca(OH)2 takes place.

The above reaction is an example of a Combination Reaction. Because in it two or more reactants combine to form a single product.

Also,

$\sf{Ca(OH)_2+CO_2\rightarrow CaCO_3+H_2O}$

When Calcium Hydroxide reacts with carbon-dioxide formation of Calcium Carbonate takes place.

The above reaction is an example of a Double Displacement Reaction. Because the exchange of ions takes place. Also, known as Precipitation Reaction, as the formation of precipitate takes place.

$\rule{200}2$

Correct Ques. 5

Teacher wrote the electronic configuration of an atom of an element as 2,8,7. Write the name of the element.

Ans. 5

Since, electronic configuration is 2,8,7(17). Means number of protons in it is 17. If protons are 17 means atomic number is 17. Therefore, the element is Chlorine (Cl).