Exams › JEE Main › Chemistry

29.5 mg of an organic compound containing nitrogen was digested according to Kjeldahl's method and the evolved ammonia was absorbed in 20 mL of 0.1 M HCl solution. The excess of acid required 15 mL of 0.1 M NaOH solution for complete neutralization. The percentage of nitrogen in the compound is

1. 59.0
2. 47.4
3. 23.7
4. 29.5

Correct answer: 23.7

Solution

The correct option is right because the amount of nitrogen is calculated based on the neutralization of the excess acid after ammonia absorption. By determining the moles of HCl initially present and subtracting the moles neutralized by NaOH, the moles of ammonia (and thus nitrogen) can be found, leading to the percentage of nitrogen in the compound.

Related JEE Main Chemistry questions

• A 100 mL sample of a urea solution contains 6.02 × 10²⁰ molecules of urea. What is the molarity of the solution? (Take Avogadro constant, N_A = 6.02 × 10²³ mol^−1.)
• When 4.9 g of H2SO4 reacts with NaCl, the products formed are 6 g of sodium hydrogen sulphate and 1.825 g of HCl. What mass of NaCl was decomposed?
• Which of the following has the least mass?
• What amount of magnesium phosphate, Mg3(PO4)2, in moles is needed to provide 0.25 mole of oxygen atoms?
• Haemoglobin has 0.33% iron by mass. If its molecular mass is about 67200 and the atomic mass of iron is 56, how many iron atoms are present in a single haemoglobin molecule?
• For the reaction 2Al(s) + 6HCl(aq) → 2Al³+(aq) + 6Cl^−(aq) + 3H₂(g), which statement is correct?

⚔️ Practice JEE Main Chemistry free + battle 1v1 →