The sulphate of a metal $M$ contains $9.87 \%$ of $M$. This sulphate is isomorphous with $ZnSO_4 \cdot 7 H_2 O$. The atomic weight of $M$ is (in $.3$)

Which of the following statements is false regarding the properties of electromagnetic waves?

$A$ radioactive nucleus (initial mass number $A$ and atomic number $Z$) emits $3 \,\alpha-$ particles and $2$ positrons. The ratio of the number of neutrons to that of protons in the final nucleus will be:

If $m_1$ and $m_2$ are the roots of the equation $x^2+(\sqrt{3}+2) x+(\sqrt{3}-1)=0$,then the area of the triangle formed by the lines $y=m_1 x, y=m_2 x$ and $y=c$ is:

Two plane mirrors $A$ and $B$ are placed parallel to each other as shown in the figure. $A$ light ray is incident at an angle of $30^{\circ}$ at a point on mirror $A$. The plane of incidence coincides with the plane of the figure. What is the maximum number of reflections (including the first one) the ray will undergo before it emerges?

In the following common emitter circuit,if $\beta = 100$,$V_{CE} = 7 \, V$,$V_{BE} = \text{Negligible}$,and $R_C = 2 \, k\Omega$,then find $I_B$ in $mA$.