Which one of the following is a covalent crystal?
Rock salt
Ice
Quartz
Dry ice
C.
Quartz
In quartz, lattice points made up of non-metal, they are held by covalent bond. Hence, quartz is a covalent crystal.
Which one of the nitrogen atoms in is the most nucleophilic?
III
I
II
All three nitrogen atoms are equally strong nucleophilic centres
Which one of the following is the most energetic conformation of cyclohexane?
Boat
Twisted boat
Chair
Half-chair
Which one of the following is an intermediate in the reaction of benzene with CH3Cl in the presence of anhydrous AlCl3?
Cl-
CH
CH
Formic acud is a stronger acid than acetic acid. This can be explained using
+M effect
-I effect
+I effect
-M effect
Which one of the following statements is false?
During roasting, moisture is removed from the ore
The ore is freed from almost all non-metallic impurities
Calcination of ore is carried out in the absence of any blast of air
The concentrated zinc blende is subjected to calcination during its extraction by pyrometallurgy
In chromite ore, the oxidation number of iron and chromium are respectively
+3, +2
+3, +6
+2, +6
+2, +3