$A$ compound absorbs light in the wavelength region $490-500 \ nm$. Its complementary colour is

The temperature of $5$ moles of a gas at constant volume is changed from $100^{\circ} C$ to $120^{\circ} C$. The change in internal energy is $80 \ J$. The total heat capacity of the gas at constant volume in $J/K$ is:

The equation $12x^2 + 7xy + ay^2 + 13x - y + 3 = 0$ represents a pair of perpendicular lines. Then the value of $a$ is

If a number is chosen at random from the four-digit numbers formed by using the digits $0, 1, 2, 3, 4, 6$ without repetition,then the probability that it is divisible by $4$ is:

The current through an ideal $PN$-junction diode shown in the following circuit diagram will be ..... $mA$.

The radioactivity of a given sample of whisky due to tritium (half-life $12.3$ years) was found to be only $3\%$ of that measured in a recently purchased bottle marked "$7$ years old". The sample must have been prepared about: