30
Q:

NH3 oxidation number?

A) -1 B) +1
C) 0 D) -3

Answer:   C) 0



Explanation:

NH3, Ammonia is a neutral compound as the individual oxidation numbers elements that make up the compound NH3 are Nitrogen (N) and Hydrogen (H) sum to zero. 

We do not speak of the oxidation number of a molecule. We can speak of the oxidation numbers of the individual elements that make up the compound.

 

Here the oxidation number of Nirogen is -3 and that of Hydrogen is +1.

Now, NH3 = 1(-3) + 3(+1) = -3 + 3 = 0.

Q:

The percentage of nitrogen in the air is about

A) 74% B) 76%
C) 78% D) 80%
 
Answer & Explanation Answer: C) 78%

Explanation:
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8 857
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

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2 26456
Q:

Which of the following is a metal?

 

A) Sulphur B) Nitrogen
C) Oxygen D) No option is correct
 
Answer & Explanation Answer: D) No option is correct

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1 9258
Q:

Which of the following group is NOT Dobereiner Triads?

 

A) Li, Na, K B) N, P Au
C) Cl, Br, I D) Ca, Sr, Ba
 
Answer & Explanation Answer: B) N, P Au

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3 40786
Q:

Safety matches contain

A) Sulphur B) Phosphorus
C) Magnesium D) Potassium
 
Answer & Explanation Answer: B) Phosphorus

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3 831
Q:

Air ___________________ are the substances which contaminate the air.

A) Reactants B) Irritants
C) Resistants D) Pollutants
 
Answer & Explanation Answer: D) Pollutants

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2 784
Q:

By using which foam the Researchers from Indian Institute of Technology – Bombay have made a low cost piezo resistive vibration sensor?

A) Only Polyurethane B) Only Polyethylene
C) Both Polyurethane and Polyethylene D) Neither Poly urethane nor Polyethylene
 
Answer & Explanation Answer: B) Only Polyethylene

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5 855
Q:

Which of the following is NOT a compound?

 

A) Ammonia B) Milk
C) Sodiumchloride D) Chalk
 
Answer & Explanation Answer: B) Milk

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