On increasing the reverse bias to a large value in a $PN-$junction diode,current

Which one of the following gives a sooty flame on combustion?

Condenser $A$ has a capacity of $15 \mu F$ when it is filled with a medium of dielectric constant $15$. Another condenser $B$ has a capacity of $1 \mu F$ with air between the plates. Both are charged separately by a battery of $100 V$. After charging,both are connected in parallel without the battery and the dielectric material being removed from condenser $A$. The common potential now is.......$V$

Resin and turpentine are obtained from

Which of the following orders is correct for the property mentioned in brackets?

The depletion layer in the $p-n$ junction is caused by