Solution:
Gypsum is added in calculated quantity in order to adjust the rate of setting of cement. Alum is not present in cement.

Solution:
The purest form of water is rain water.

Solution:
The value of Avogadro Number is 6.023 × 1023.

Solution:
The atomic number of uranium is 92, and the mass number of the isotope is given as 238. Therefore, it has 92 protons, 92 electrons, and 238 — 92 = 146 neutrons.

Solution:
The next higher homologue of C6H14 is C7H16.

Solution:
As phenol is an aromatic alcohol, so FeCl3 test is a test for alcohol and esterificaton test is also a test for alcohol. The ferric chloride test is used to determine the presence or absence of phenols in a given sample (for instance natural phenols in a plant extract).

Solution:
Electrolysis of an aqueous solution of copper sulphate using copper electrodes gives copper at cathode and oxygen at anode.