In a semiconducting material,the mobilities of electrons and holes are $\mu_e$ and $\mu_h$ respectively. Which of the following is true?

The energy gap of silicon is $1.1 \, eV$. At what wavelength will silicon stop absorbing photons? (in $\mathring A$)

Assertion $(A)$: When a wire of aluminium and another wire of silicon are heated from room temperature to $80^{\circ} C$,the conductivity of aluminium decreases and that of silicon increases.
Reason $(R)$: Aluminium has a positive temperature coefficient of resistivity and silicon has a negative temperature coefficient of resistivity.

What type of semiconductor is $CdS$?

This question has Statement $1$ and Statement $2$. Of the four choices given after the Statements,choose the one that best describes the two Statements.
Statement $1$ : $A$ pure semiconductor has a negative temperature coefficient of resistance.
Statement $2$ : On raising the temperature,more charge carriers are released into the conduction band.

What is the crystalline structure of an intrinsic semiconductor?