CBSE Class 10 Answered

1.A farmer has grown the petunia flowers on his field. He observed that the colour of the flowers started changing from blue to reddish purple. • What could be the possible reason for the change in colour? ⚫ What role is played by petunia flowers? • Suggest any two substances playing the same role in the field of agriculture. • What should be added by the farmer to treat the soil? What type of reaction will take place during treatment of soil? 2. A metal X reacts with HCI to liberate gas A but its compound Y releases gas B with HCI along with the salt CaCl,. Name the metal X. • Identify gas A and how will you test for it? ⚫ Name the salt Y and give its molecular formula. • Identify gas B and how will you test for it? What type of reaction takes place when X reacts with HCI? 3. A sodium salt 'A' is used while baking a cake. It makes the cake fluffy and spongy due to the release of gas 'B'. Identify salt 'A'. ⚫ What is the common name of this salt? ⚫ Which gas is released during the process? • How will you test for gas 'B'? 4. Anita's mother asked her to store the pickle in some bowl. She kept the pickle in a brass bowl. Was she right in doing that? Why or why not?

Asked by 9414612ji | 19 Aug, 2022, 08:25: AM

Expert Answer

Dear Student,

Kindly ask one query at a time.

Answer for first chemistry question,

Qus: A metal X reacts with HCI to liberate gas A but its compound Y releases gas B with HCI along with the salt CaCl,.

Name the metal X.

• Identify gas A and how will you test for it?

Name the salt Y and give its molecular formula.

• Identify gas B and how will you test for it? What type of reaction takes place when X reacts with HCI?

The answer is given below,

Salt of X Metal i.e Y reacts with HCl to produce salt CaCl₂ and gas B.

(i)As the product CaCl₂ is a calcium salt, we can conclude that the reactant Y salt is a Calcium metal salt.

(ii)Carbonates of metal on reacting with HCl produce Chlorides of metal along with release CO₂ gas.

From (i) and (ii), the salt must be CaCO₃ and the reaction would be as below,

CaCO₃ + HCl → CaCl₂ + CO₂↑

As Y is CaCO₃, hence, X must be Calcium metal.

Metals on reaction with HCl produce corresponding chlorides and hydrogen gas. This is Displacement reaction wherein metal displaces hydroen from HCl to form metal chlorides.

Ca + HCl → CaCl₂ + H₂↑

Thus,

X = Ca

Y = CaCO₃

A = H₂ gas

The gas A is hydrogen gas which can be confirmed by holding burning candle in the released gas. Hydrogen gas burns with pop sound.

B = CO₂ gas

The gas B is carbon dioxide which can be confirmed by lime water test. Carbon dioxide turns lime water milky.

Answered by | 19 Aug, 2022, 12:52: PM