GATE Questions

Q:

What is the oxidation number of carbon in NaHCO3?

A) -4 B) -3
C) +4 D) +2
 
Answer & Explanation Answer: C) +4

Explanation:

The given compound is NaHCO3 Sodium bicarbonate which is commonly known as Baking soda.

Oxidation numbers are the charges on ions. When a neutral atom loses electrons it becomes positively charged. When a neutral atom gains electrons it becomes negatively charged.

 

Here the C represents the oxidation state of carbon in this compound. Compounds are electrically neutral, which is why we set the sum of the oxidation states equal to zero.

Sodium has a +1 oxidation state. Hydrogen has a +1 oxidation state. Oxygen has a -2 oxidation state. There are three oxygen atoms, which means the total oxidation state provided by both oxygen ions is -6. Adding up these oxidation states we get:

1 + 1 + (-6) + C = 0

-4 + C = 0

=> C = 4


This means the oxidation state of carbon in this compound is +4.

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1 5956
Q:

You drive to the store at 20 kmph and return by the same route at 30 kmph. Discounting the time spent at the store, what was your average speed ?

A) 25 kmph B) 24 kmph
C) 26 kmph D) 22 kmph
 
Answer & Explanation Answer: B) 24 kmph

Explanation:

Average speed=total distance/total time
Let distance to store be  K
then, total time =(K/20)+(K/30)=K/12
and, total time =(2K)
so average speed= 2K / (K/12) = 24kmph.

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Filed Under: Time and Distance
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3 5955
Q:

12 days payment to the servant in a cloth showroom in festival season is Rs. 400 plus one shirt. The servant leaves after 9 days and recieves Rs. 280 and a shirt. What is the price of the shirt ? 

A) Rs. 80 B) Rs. 120
C) Rs. 70 D) Rs. 100
 
Answer & Explanation Answer: A) Rs. 80

Explanation:

The servant worked for 9 days instead of 12 days, he should receive 9/12 of his total payment

Let the price of 1 shirt be Rs. S 

i.e., 3/4 (400 + S).

However, the question states that the servant receive Rs. 280 + S where S is the price of the shirt.

By equating the two equations we get 3/4 (400 + S) = 280 + S.

Therefore, Price of the shirt S = Rs. 80.

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22 5954
Q:

The ratio between the number of sheep and the number of horses at the Stewar farm is 4 to 15. If each of horse is fed 110 ounces of horse food per day and the farm needs a total 13200 ounces of horse food per day. what is number sheep in the form ?

A) 32 B) 36
C) 44 D) 52
 
Answer & Explanation Answer: A) 32

Explanation:

Given ratio of number of sheep and horses = 4 : 15
Let number of sheep and horses are 4k and 15k
Number of horses = 13200/110 = 120
Now 15K = 120 and k = 8
Number of sheep = 4k = (4 x 8) = 32

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8 5929
Q:

What has 3 feet but cannot walk?

Answer

We know that 1 yard = 3 feet. 


 


A yardstick which is used for measurement has 3 feet long but it cannot walk.


 

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7 5918
Q:

Find the speed of stream if a boat covers 36 km in downstream in 6 hours which is 3 hours less in covering the same distance in upstream?

A) 1.5 kmph B) 1 kmph
C) 0.75 kmph D) 0.5 kmph
 
Answer & Explanation Answer: B) 1 kmph

Explanation:

Speed of the boat upstream = 36/9 = 4 kmph

Speed of the boat in downstream = 36/6 = 6 kmph

Speed of stream = 6-4/2 = 1 kmph

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18 5918
Q:

A shopkeeper sells two articles at Rs.1000 each, making a profit of 20% on the first article and a loss of 20% on the second article. Find the net profit or loss that he makes?

A) 2% B) 4%
C) 3% D) 2.5%
 
Answer & Explanation Answer: B) 4%

Explanation:

SP of first article = 1000

Profit = 20%

CP = 100100+P×SP= 5000/6 = 2500/3


SP of second article = 1000

Loss = 20%

CP = 100100-L×SP= 5000/4 = 1250


Total SP = 2000

Total CP = 25003+ 1250 = 6250/3

CP is more than SP, he makes a loss.

Loss = CP-SP = (6250/3)- 2000 = 250/3


Loss Percent =250362503×100= 4%

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5 5917
Q:

What are the sides of the dna ladder made of

A) nitrates and sugars B) sugars and hydrates
C) sugars and phosphates D) phosphates and nitrates
 
Answer & Explanation Answer: C) sugars and phosphates

Explanation:

DNA is a double-stranded molecule twisted into a helix. The shape of DNA is a double helix, which is like a twisted ladder. The sides of the ladder are made of alternating sugar and phosphate molecules. Deoxyribose, which is a pentose, and a phosphate group are the two molecules together form the two sides of the DNA. The rungs of the ladder are pairs of 4 types of nitrogen bases.

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5 5914