Chemistry Questions

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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Q:

What is the gram formula mass of K2CO3?

A) 147 B) 138
C) 129 D) 116
 
Answer & Explanation Answer: B) 138

Explanation:

The gram formula mass of a compound is nothing but the molar mass.

The molar mass of K2CO3 (Potassium Carbonate) is given by

Atomic weights of individual elements are

 

K (Potassium) = 39 g

C (Carbon) = 12 g

O (Oxygen) = 16 g

 

Hence, that of K2CO3 = 39(2) + 12 + 16(3)

= 78 + 12 + 48

= 138.

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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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Q:

Washing soda is the common name for

A) Sodium Bicarbonate B) Calcium Carbonate
C) Sodium Carbonate D) Calcium Bicarbonate
 
Answer & Explanation Answer: C) Sodium Carbonate

Explanation:

Washing soda is the common name for Sodium Carbonate (Na2CO3). It is also called as Soda Ash.

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Q:

Which one of the following is not true for minerals?

A) they can be a liquid, solid, or glass B) they can be identified by characteristic physical properties
C) they have a specific, internal, crystalline structure D) they have a specific, predictable chemical composition
 
Answer & Explanation Answer: A) they can be a liquid, solid, or glass

Explanation:

A mineral is a naturally occurring, inorganic solid, with a definite chemical composition. They cannot be in liquid or gas state. They exists only in solid state.

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Q:

Ultimate strength to cement is provided by

A) Di-calcium silicate B) Tricalcium silicate
C) Tetra calcium alumino ferrite D) Tri-calcium aluminate
 
Answer & Explanation Answer: A) Di-calcium silicate

Explanation:
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Q:

Which of the following is used to preserve specimens in the biology laboratory?

A) Phenol B) Benzaldehyde
C) Formaldehyde D) Acetic acid
 
Answer & Explanation Answer: C) Formaldehyde

Explanation:

A 40% solution of Formaldehyde known as Formalin is used in the preservation of biological specimens because of its hardening action on proteins. 

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Q:

Which of the following elements has the highest electronegativity?

A) Chlorine B) Bromine
C) Fluorine D) Helium
 
Answer & Explanation Answer: C) Fluorine

Explanation:

Electronegativity refers to the ability of an atom to attract shared electrons in a covalent bond. The higher the value of the electronegativity, the more strongly that element attracts the shared electrons.

Electronegativity increases from bottom to top in groups, and increases from left to right across periods. Thus, fluorine is the most electronegative element and lithium is the least.

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