When acetaldehyde is heated with Fehling solution,a red precipitate is formed. Which of the following is that?

The oxidation state and covalency of $Al$ in $[AlCl(H_2O)_5]^{2+}$ are respectively

One junction of a certain thermoelectric couple is at a fixed temperature $T_r$ and the other junction is at temperature $T$. The thermo-electromotive force for this is expressed by $E=k(T-T_r)[T_0-\frac{1}{2}(T+T_r)]$. At temperature $T=\frac{1}{2} T_0$,the thermoelectric power is

Which of the following is absent in polluted water?

$A$ student is to answer $10$ out of $13$ questions in an examination such that he must choose at least $4$ from the first $5$ questions. The number of choices available to him is

$A$ metal crystallises in a face-centred cubic $(FCC)$ structure. If the edge length of its unit cell is $a$,the closest approach between two atoms in the metallic crystal will be: