Chemistry - Study Mode

[#201] Quartz is a crystalline form of
Correct Answer

(C) Silica

Explanation

Solution: Quartz is made up of a continuous framework of SiO 4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO 2 . Tridymite and cristobalite are hightemperature polymorphs of SiO 2 that occur in highsilica volcanic rocks. Coesite is a denser polymorph of quartz found in some meteorite impact sites and in metamorphic rocks.

[#202] Urea is a
Correct Answer

(C) Nitrogenous fertilizer

Explanation

Solution: Urea is a nitrogenous fertilizer.

[#203] Oxygen has (+) oxidation number only in
Correct Answer

(A) OF 2

Explanation

Solution: In case of OF 2 , oxygen is not the most electronegative element. The fluorine is more electronegative and has an oxidation state of -1. In this case, the oxygen has an oxidation state of +2.

[#204] The oxidation number of nickel in K 4 [Ni(CN) 4 ] is
Correct Answer

(A) Zero

Explanation

Solution: The oxidation number of nickel in K 4 [Ni(CN) 4 ] is zero.

[#205] How many neutrons are there in 92 U 238 atom ?
Correct Answer

(C) 146

Explanation

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.