Chemistry Questions

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
 
Answer & Explanation Answer: A) A & B

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:

Which compound matches the IR Spectrum?

 

spectr1525848245.jpg image

A) 1, 5 – hexadiene B) 3 – Hexanol
C) Trans – 4 – octene D) None of the above
 
Answer & Explanation Answer: A) 1, 5 – hexadiene

Explanation:

3 – Hexanol:


image

There is no alcohol stretch present in the spectrum. Therefore, the above structure is not suitable for the given spectrum.

 

Trans – 4 – octene:


image

There is no vinyl bending present in the spectrum. Therefore, the above structure is not suitable for the given spectrum.


1, 5 – hexadiene:


image

The vinyl bending and other stretches were matched with the above structure.

 

 

Hence, the c = c stretch, vinyl bending and image stretch were matched with the above structure.

Therefore, the given spectrum belongs to 1, 5 – hexadiene.

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Q:

Which of the following reactions are exothermic?

 

1)   C + O2   CO22)  2Mg + O2   2MgO3)  CuSO4 + 5H2O   CuSO4.5H2O4)  All the above

A) 1 B) 2
C) 3 D) 4
 
Answer & Explanation Answer: 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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Q:

Burning Magnesium ribbon produces white ash, which dissolves in water to form____.

 

A) Magnesium Halides B) Magnesium Oxide
C) Magnesium Hydroxide D) Magnesium Sulphate
 
Answer & Explanation Answer: C) Magnesium Hydroxide

Explanation:
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Q:

Methane contributes towards global warming so it is called a _________________ gas.

 

A) poisonous B) carcinogenic
C) infectious D) greenhouse
 
Answer & Explanation Answer: D) greenhouse

Explanation:
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Q:

What is the Iupac name for the compound shown below.

                           clbr1527920257.png image

A) 1-Bromo-3-chlorocyclohexene B) 2-Bromo-6-chlorocyclohex-1-ene
C) 6-Bromo-2-chlorocyclohexene D) 3-Bromo-1-chlorocyclohex-1-ene
 
Answer & Explanation Answer: D) 3-Bromo-1-chlorocyclohex-1-ene

Explanation:

In chemical nomenclature, the IUPAC nomenclature of organic chemistry is a systematic method of naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry (IUPAC).

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Q:

Mg+O2=MgO

Balance the above Chemical equation?

A) 2Mg + O2 ----> 2MgO B) 2Mg + O ----> 2MgO
C) 2Mg + O ----> MgO2 D) 2Mg + O2 ----> MgO2
 
Answer & Explanation Answer: A) 2Mg + O2 ----> 2MgO

Explanation:

Given Equation is 

Mg + O2  MgO

Balancing the Chemical Equation is nothing but Conservation of Matter. As Matter is Neither created nor Destroyed, it must be conserved.

Here we have 1 Mg and 2 O on the left side and 1 Mg and 1 O on the right side

To balance that, add 1 Mg on the left side so that it becomes 2 Mg and 2 O on the left side

i.e,

2 Mg + O2  2 MgO

Here it has 2 Mg & 2 O on the left side and 2 Mg and 2 O on the right side and the Chemical equation is Balanced.

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Q:

An element with an atomic number of ___ will form a basic oxide.

 

A) 20 B) 7
C) 6 D) 17
 
Answer & Explanation Answer: A) 20

Explanation:
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