Which of the following allotrope of carbon is a constituent of a lead pencil?
Graphite
Diamond
Lampblack
Soot
Correct answer is A
When an element exists in more than one crystalline form, those forms are called allotropes; the two most common allotropes of carbon are diamond and graphite.
Graphite is used in pencils and lubricants. It is a good conductor of heat and electricity. Its high conductivity makes it useful in electronic products such as electrodes, batteries, and solar panels.
The gas that is most useful in protecting humans against solar radiation is?
chlorine
ozone
carbon (IV) oxide
hydrogen sulphide
Correct answer is B
The ozone layer in the stratosphere absorbs a portion of the radiation from the sun, preventing it from reaching the planet's surface.
Most importantly, it absorbs the portion of UV light called UVB.
The gasification of coke is used for the manufacturing of?
producer gas
natural gas
synthetic gas
industrial gas
Correct answer is C
Gasification is a process that converts biomass- or fossil fuel-based carbonaceous materials into synthetic gases
Hydrogen sulphide gas can act as?
an oxidizing agent
a dehydrating agent
a bleaching agent
a precipitating agent
Correct answer is D
When Hydrogen sulphide gas is bubbled through solutions of such metals, the colored sulphides are precipitated.
Hydrogen sulphide is a also strong reducing agent.
The oxidation of ammonia in excess air produces?
NO
N2O
NO2
N2O4
Correct answer is A
In the presence of heated platinum catalyst, ammonia reacts with excess air to produce nitrogen (II) oxide, NO, (instead of nitrogen) and water.