Propanal on treatment with dilute sodium hydroxide forms

Assertion : Bond angle of $H_2S$ is smaller than $H_2O$.
Reason : Electronegativity of the central atom increases,bond angle decreases.

Degenerate electron pressure will not be sufficient to prevent core collapse of a white dwarf if its mass becomes $n$ times the solar mass. The value of $n$ is:

When substance $A$ reacts with water,it produces a combustible gas $B$ and a solution of substance $C$ in water. When another substance $D$ reacts with solution $C$,it produces the same gas $B$ even when reacting with dilute sulfuric acid at room temperature. $A$ imparts a golden yellow color to the non-luminous flame of a Bunsen burner. What are $A$,$B$,$C$,and $D$ respectively?

Which one of the following equations represents the variation of viscosity coefficient $(\eta)$ with temperature $(T)$?

In a single slit diffraction experiment, the first minimum for red light $(\lambda = 660 \, nm)$ coincides with the first secondary maximum of some other wavelength $\lambda'$. The value of $\lambda'$ is ...... $\mathring{A}$.