In the experimental setup given below, it is observed that on passing the gas produced in the reaction in the solution 'X' the solution 'X' first turn milky and then colourless.

The option that justifies the above stated observation is that 'X' is aqueous calcium hydroxide and

1. it turns milky due to carbon dioxide gas liberated in the reaction and after sometime it becomes colourless due to formation of calcium carbonate.

2. it turns milky due to formation of calcium carbonate and on passing excess of carbon dioxide it becomes colourless due to formation of calcium hydrogen carbonate which is soluble in water.

3. it turns milky due to passing of carbon dioxide through it. It turns colourless as on further passing carbon dioxide, sodium hydrogen carbonate is formed which is soluble in water.

4. the carbon dioxide liberated during the reaction turns lime water milky due to formation of calcium hydrogen carbonate and after some time it turns colourless due to formation of calcium carbonate which is soluble in water.

The table below has information regarding pH and the nature (acidic/basic) of four different solutions. Which one of the options in the table is correct ?

The emission of brown fumes in the given experimental set-up is due to

1. thermal decomposition of lead nitrate which produces brown fumes of nitrogen dioxide.
2. thermal decomposition of lead nitrate which produces brown fumes of lead oxide.
3. oxidation of lead nitrate forming lead oxide and nitrogen dioxide.
4. oxidation of lead nitrate forming lead oxide and oxygen.

A metal 'X' is used in thermite process. When X is burnt in air it gives an amphoteric oxide 'Y'. 'X' and 'Y' are respectively :

1. Fe and Fe₂O₃
2. Al and Al₂O₃
3. Fe and Fe₃O₄
4. Al and Al₃O₄