Chemistry Questions

Q:

Which of the Following is an Amorphous solid?

 A) Quartz Glass(Sio2) B) Chrome Alum C) Silicon Carbide(SiC) D) Graphite

Explanation:

An amorphous or non-crystalline solid is a solid that lacks the long-range order that is characteristic of a crystal. In Brief, An amorphous solid is any noncrystalline solid in which the atoms and molecules are not organized in a definite lattice pattern. Such solids include glass, plastic, and gel.

Quartz glass (SiO2) is an amorphous solid due to its short range order of constituent particles. Note Quartz is a crystalline solid while quartz glass is an amorphous solid.

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40 15417
Q:

The discovery of neutron became very late because

 A) it is present in nucleus B) it is a fundamental particle C) it does not move D) it does not carry any charge

Explanation:

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Q:

The entropy change involved in the isothermal reversible expansion of 2 moles of an ideal gas from a volume of 10 $dm3$ at 27°C is to a volume of 100 $dm3$

 A) 42.3 J/ mole / K B) 38.3 J/ mole / K C) 35.8 J/ mole / K D) 32.3 J/ mole / K

Explanation:

$∆s=nRlnv2v1$

= $2.303×2×8.314×log10010$ =  $mol-1$$k-1$

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37 14609
Q:

Which of the following reactions are exothermic?

 A) 1 B) 2 C) 3 D) 4

Explanation:

Here all the given options are Exothermic reactions. Exothermic reactions are those reactions which involves the release of heat.

Generally all the combining reactions are exothermic in nature.

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8 14498
Q:

How many electrons are there in Na+

 A) 1 B) 10 C) 11 D) 12

Explanation:

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Q:

Temporary hardness is due to the presence of

 A) Calcium carbonate B) calcium bicarbonate C) magnesium sulphate D) calcium sulphate

Explanation:

Temporary hardness is due to the presence of soluble bicarbonates of calcium and magnesium in water. Permanent hardness is due to the presence of sulphates and chlorides of calcium and magnesium.

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35 14307
Q:

which of the following are chemical changes?

A) Cooking of Food

B) Digestion of Food

C) Freezing of water

D) Water is heated up

 A) A & B B) A, B & C C) C & D D) All the above

Explanation:

A) Cooking of Food  ------ Chemical Change

B) Digestion of Food ----- Chemical Change

C) Freezing of water ----- Physical Change

D) Water is heated up ---- Physical Change

because here the chemical composition of the substance changes in A & B only.

Since we know that, If the chemical composition is changing then it is a chemical change and if the chemical composition is remaining the same, then it is a physical change.

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Q:

' Misch metal ' is widely used in manufacture of which of the following

 A) Material of car brake B) Smoke detectors C) Cigarette lighters D) Emergency lights