Carbon and hydrogen are estimated by

Liebig’s method

The correct answer is option 1. Liebig’s method.

Liebig’s method is a classical technique used to determine the carbon and hydrogen content in organic compounds. Here's a detailed explanation of the method:

Combustion: The organic compound is burned in the presence of excess oxygen. This combustion converts all the carbon present in the compound to carbon dioxide (CO₂) and all the hydrogen to water (H₂O).

Absorption of Products: The combustion products (CO₂ and H₂O) are then passed through two specific absorbents:

Calcium chloride (CaCl₂) is used to absorb the water. The increase in the weight of the calcium chloride absorbent is used to calculate the amount of water produced.

Potassium hydroxide (KOH) or a similar substance is used to absorb the carbon dioxide. The increase in the weight of the potassium hydroxide absorbent is used to calculate the amount of carbon dioxide produced.

Calculation: The amounts of CO₂ and H₂O absorbed are measured, and from these measurements, the amounts of carbon and hydrogen in the original sample are calculated.

The amount of carbon is determined by calculating the amount of CO₂ produced.

The amount of hydrogen is determined by calculating the amount of H₂O produced.

Steps in Liebig’s Method:

Preparation: Weigh a known amount of the organic compound.

Combustion: Burn the sample in a combustion tube with a stream of oxygen.

Absorption: Pass the resulting gases through tubes containing calcium chloride and potassium hydroxide.

Weighing: Weigh the tubes before and after the experiment to determine the mass of CO₂ and H₂O absorbed.

Calculations:

Calculate the mass of carbon in the sample using the increase in weight of the KOH tube (which absorbed CO₂).

Calculate the mass of hydrogen in the sample using the increase in weight of the CaCl₂ tube (which absorbed H₂O).

By accurately measuring these increases in weight, the proportion of carbon and hydrogen in the original sample can be determined.

Thus, the correct answer is: (1) Liebig’s method