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:

What are the substances which mimic the natural chemical messengers?

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

The sum of the spin only magnetic moment values $(in \ B.M.)$ of $\left[ Mn ( Br )_6\right]^{3-}$ and $\left[ Mn ( CN )_6\right]^{3-}$ is $....$ .

Which option is correct to match section $A$ with section $B$?

In the adjoining circuit diagram,the readings of the ammeter and voltmeter are $2 \ A$ and $120 \ V$,respectively. If the value of $R$ is $75 \ \Omega$,then the voltmeter resistance will be (in $\Omega$):