Chemistry Questions

Q:

Alloy of copper and zinc is called

A) Bronze B) Gold
C) Silver D) Brass
 
Answer & Explanation Answer: D) Brass

Explanation:

alloy_of_copper_and_zinc_is_called1556100441.jpg image

 

Alloy of copper and zinc is called as Brass.

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Q:

Tetraethyl lead is used as

A) Fire extinguisher B) Gasoline additive
C) Mosquito repellent D) Pain killer
 
Answer & Explanation Answer: B) Gasoline additive

Explanation:

Tetraethyl lead is a highly toxic compound used as a gasoline additive.

Tetraethyl lead abbreviated as TEL, is an organo lead compound with the formula (CH3CH2)4Pb. It is a petro-fuel additive which in turn caused increased vehicle performance. This is also used as an antiknock agent in gasoline and jet fuels. Tetraethyl lead is absorbed rapidly by the skin, the lungs, and the gastrointestinal tract. It is converted to triethyl lead, which might be responsible for its toxicity.

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8 2555
Q:

Dust particles in the air of large industrial cities are removed by 

A) Sedimentation B) Electrophoresis
C) Tyndall effect D) Brownian movement
 
Answer & Explanation Answer: B) Electrophoresis

Explanation:

Dust particles such as coal dust(smoke) are fine particle of a solid (carbon in the case of smoke) dispersed in air. They are colloidal systems and the particles are charged either positive or negative. In an applied electrical field, they are attracted towards the opposite electrodes. Movement of the particles towards the electrodes is known as 'electrophoresis'. Hence electrophoresis is applied to remove smoke within the chimeny itself without allowing it to escape into the air and cause nuisance.

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3 2547
Q:

What does the Aufbau Principle state

A) Electrons will be added to an atom starting from the lowest possible level or sublevel. B) Electrons will be added to an atom only if the orbitals are different colors.
C) Electrons will be added to an atom in a random order. D) Electrons will be added to an atom in a symmetrical manner.
 
Answer & Explanation Answer: A) Electrons will be added to an atom starting from the lowest possible level or sublevel.

Explanation:

The Aufbau Principle states that in the ground state of an atom, an electron enters the orbital with lowest energy first and subsequent electrons are fed in the order of increasing energies.

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Q:

Which of the following is not soluble in water?

A) copper(II) hydroxide B) sodium chloride
C) silver nitrate D) potassium sulfate
 
Answer & Explanation Answer: A) copper(II) hydroxide

Explanation:

Sodium chloride:

The solubility rules tell you that all halides are soluble with the exception of those formed with siver, mercury, and lead ions. Since this is not the case here, sodium chloride will be soluble.

 

Silver nitrate:

It is soluble because all nitrates are soluble, without exception.

 

Potassium sulfate:

It is soluble because all sulfates are soluble with the exception of those formed with silver, calcium, barium, mercury, lead, and strontium ions.

 

Copper (II) hydroxyde:

It is insoluble because all hydroxides are insoluble with the exception of those formed with alkali metal ions and barium.

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2 2528
Q:

If people sleep in closed rooms where charcoal fire is burning , they die due to 

A) carbon monoxide B) carbon dioxide
C) methane D) phosgene
 
Answer & Explanation Answer: A) carbon monoxide

Explanation:

A closed room is aplace where charcoal is burnt in limited supply of air. There is every chance for the formation of the deadly poisonous carbon monoxide, which when inhaled, reacts with the iron in haemoglobin of blood and prevents the supply of oxygen. It is said to be treacherous as there can be no previous warning of its presence because it is an odourless and colourless gas.

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2 2516
Q:

The atoms of the elements which have same number of neutrons are called

A) Isobars B) Isotopes
C) Isotones D) None
 
Answer & Explanation Answer: C) Isotones

Explanation:
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4 2514
Q:

The function of nitrogen in air is 

A) to make air a moderate supporter of combustion B) to maintain the density of air constant
C) to prevent the hydrogen in air from exploding D) to reduce the poisonous nature of ozone in air
 
Answer & Explanation Answer: A) to make air a moderate supporter of combustion

Explanation:

If air contained all oxygen and no nitrogen, everything would have burnt off

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