Metals and Non-Metals — Science STD 10 — Question

What will happen if a solution of sodium hydrocarbonate is heated? Give the equation of the reaction involved.

For each of the following triads, name the element with the characteristics specified below:

	Elements	Least atomic radius	Chemically least reactive
(i)	F, Cl, Br	.....................	.....................
(ii)	Li, Na, K	.....................	.....................

You have been provided with two test tubes. One of them contains distilled water and the other contain acid solution. How will you find out which of the test tube contains water without testing the contents of the test tube?

What is meant by the ‘concentration of ore’?

A milkman adds a very small amount of baking soda to fresh milk.

1. Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
2. Why does this milk take a long time to set as curd?

Draw the electron-dot structure of a hydrogen chloride molecule:

1. Which inert gas does the H atom in HCl resemble in electron arrangement?
2. Which inert gas does the Cl atom in HCl resemble in electron arrangement?

An element ‘A’ has two electrons in the outermost shell of its atom and combines with an element ‘B’ having seven electrons in the outermost shell, forming the compound AB₂. The compound when dissolved in water conducts electric current. Giving reasons, state the nature of chemical bond in the compound.

Explain the pH change as the cause of tooth decay. How can tooth decay caused by pH change be prevented?

Explain why, metals usually do not liberate hydrogen gas with dilute nitric acid.

A gas is evolved when ethanol reacts with sodium. Name the gas evolved and also write the balanced chemical equation of the reaction involved.