Which of the following sulfate salts has the highest solubility in water?

The number of moles of electrons required to deposit $36 \ g$ of $Al$ from an aqueous solution of $Al(NO_3)_3$ is (At. wt. of $Al = 27$)

Two resistances of $400\,\Omega$ and $800\,\Omega$ are connected in series with a $6\,V$ battery of negligible internal resistance. $A$ voltmeter of resistance $10,000\,\Omega$ is used to measure the potential difference across the $400\,\Omega$ resistor. The error in the measurement of potential difference (in volts) is approximately:

The volume-temperature graphs of a given mass of an ideal gas at constant pressures are shown below. What is the correct order of pressures?

If $a \neq 0, b \neq 0, c \neq 0, a \times b = 0$ and $b \times c = 0$,then $a \times c$ is equal to

Match the appropriate pairs from List-$I$ and List-$II$ :

List-$I$	List-$II$
$1$. Nitrogen molecules	$(A)$ Continuous spectrum
$2$. Incandescent solids	$(B)$ Absorption spectrum
$3$. Fraunhoffer lines	$(C)$ Band spectrum
$4$. Electric arc between iron rods	$(D)$ Emission spectrum