Subject Experts Solutions for Chapter: Some Important Elements and their Compounds, Exercise 2: PRACTICE QUESTIONS (COMPETITION WING)

Ranchu's father is working in a fertiliser industry. One day at home he heard his father making a suggestion to his colleague that 'between nitrate salts and ammonium salts, nitrate salts are preferable for use as a fertiliser.' The next day Ranchu asked his brother the reason for their father's suggestion. What answer did his brother give? 

Thermoplastics can be moulded again and again, whereas thermosettings cannot be moulded. Give a reason. 

Why is the compound $\mathrm{AgCl}$ used in photo gray lenses? 

Bleaching powder in cold water is an excellent bleaching agent. But it cannot act as a good bleaching agent when dissolved in hot water. Why? 

Hydrofluoric acid cannot be stored in glass bottles like all other acids. Give a reason. 

Certain phosphates are helpful in making hard water soft. Which phosphates are used and how do they help in making water soft? 

Both ${\mathrm{H}}_2{\mathrm{SO}}_4$ and ${\mathrm{HNO}}_3$ cause damage to the skin when the skin comes in contact with them. Compare and contrast the reasons. 

Nitric acid attacks all the metals except noble metals but the nature of products of the same metal along with corresponding nitrates depends upon the concentration of ${\mathrm{HNO}}_3$. Explain.