Which from the following dopants is used in germanium to produce $p-$type semiconductor?

Certain crystals produce electric signals on application of pressure. This phenomenon is called

Which one of the following is used as a piezoelectric material?

Which of the following is an example of an ionic crystal solid?

Match the following magnetic properties with their respective domain alignments shown in the image.

$A$. Antiferromagnetism	$I$. $\uparrow \downarrow \uparrow \downarrow \uparrow \downarrow$
$B$. Ferromagnetism	$II$. $\uparrow \uparrow \uparrow \uparrow \uparrow \uparrow$
$C$. Ferrimagnetism	$III$. $\uparrow \uparrow \downarrow \uparrow \uparrow \downarrow$

The correct matching is:

'Stability of a crystal is reflected in the magnitude of its melting points'. Comment. Collect melting points of solid water,ethyl alcohol,diethyl ether and methane from a data book. What can you say about the intermolecular forces between these molecules?