Which one of the following statements is wrong?

What is the catalyst used in the conversion of acetaldehyde to acetic acid?

If $1^{\circ} = \alpha$ radians,then the approximate value of $\cos(60^{\circ} 1^{\prime})$ is

The solution of $\cos y + (x \sin y - 1) \frac{dy}{dx} = 0$ is

True nucleus is absent in

$A$ vessel contains hydrogen and nitrogen gases in the ratio $2:3$ by mass. If the temperature of the mixture of the gases is $30^{\circ} C$, then the ratio of the average kinetic energies per molecule of hydrogen and nitrogen gases is $($Molecular mass of hydrogen $=2$ and molecular mass of nitrogen $=28)$