239) Which of the following gases is coloured:

240) When CO₂ is passed into lime water, it turns milky. When excess of CO₂ is passed, milkiness disappears because:

241) Black ppt. A dissolves in HNO₃ giving B, which gives white ppt. C with NH₄OH. C on reaction with HCl gives solution D, which gives white turbidity on addition of water. What is D?

242) A white precipitate is obtained on hydrolysis of:

243) Which of the following combines with Fe (II) ions to form a brown complex?