Many transition metals from interstial compounds. Which of the following characteristics of these interstitial compounds is/are correct :
$\left(I\right)$ They have high melting points, higher than those of pure metals

$\left(II\right)$ They are very hard

$\left(III\right)$ They retain metalic conductivity

$\left(IV\right)$ They are chemically more reactive than the pure metals

Q. Which of the following is true for all metals?
(a) They are hard solids.
(b) They have high melting and boiling points.
(c) They have 1−3 valence electrons.
(d) They are malleable and ductile.

Q. Transition metals are hard and lustrous substances with high melting points and form highly coloured compounds. Which of the following is not transition metals?

Q. Choose the correct answer from the options given below:
(i) In the periodic table alkali metals are placed in the group ___________
(a) 1
(b) 11
(c) 17
(d) 18

(ii) Which of the following properties do not match with elements of the halogen family?
(a) They have seven electrons in their valence shell.
(b) They are highly reactive chemically.
(c) They are metallic in nature.
(d) They are diatomic in their molecular form.

Q. Many transition metals form interstitial compounds. The characteristics of these interstitial compounds are:
(I) They have high melting points, higher than those of pure metals
(II) They are very hard
(III) They retain metallic conductivity
(IV) They are chemically more reactive than the pure metals

Q. What are interstitial compounds? Why do these compounds have higher melting points than corresponding pure metals?