Exams


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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Q:

In a race of 1000 m, A can beat by 100 m, in a race of 800m, B can beat C by 100m. By how many meters will A beat C in a race of 600 m ?

A) 127.5 m B) 254 m
C) 184 m D) 212 m
 
Answer & Explanation Answer: A) 127.5 m

Explanation:

When A runs 1000 m, B runs 900 m and when B runs 800 m, C runs 700 m.

When B runs 900 m, distance that C runs = (900 x 700)/800 = 6300/8 = 787.5 m.

In a race of 1000 m, A beats C by (1000 - 787.5) = 212.5 m to C.

In a race of 600 m, the number of meters by which A beats C

= (600 x 212.5)/1000 = 127.5 m.

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36 6575
Q:

The Ghodazari Wildlife Sanctuary (GWS) will come up in which state?

A) Maharashtra B) Karnataka
C) Tamil Nadu D) Odisha
 
Answer & Explanation Answer: A) Maharashtra

Explanation:

The Maharashtra Government has recently approved Ghodazari Wildlife Sanctuary in Chandrapur district as a new wildlife sanctuary in the state.

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Q:

Which type of molecule is CF4?

A) nonpolar, with a symmetrical distribution of charge B) polar, with an asymmetrical distribution of charge
C) nonpolar, with an asymmetrical distribution of charge D) polar, with a symmetrical distribution of charge
 
Answer & Explanation Answer: A) nonpolar, with a symmetrical distribution of charge

Explanation:

CF4 is tetrahedral.

Since the four 'F' atoms have the same electronegativity values, there is no bias in electron distribution toward any one.

 

Therefore, electron/charge distribution is symmetrical, which also means that the molecule is nonpolar.

 

Hence, CF4 is nonpolar molecule with a symmetrical distribution of charge.

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Q:

The average age of the district level hockey team of eleven is 22 years.The average age gets increased by 1 year when the coach age is also included.what is the age of the coach ?

A) 33 yrs B) 34 yrs
C) 35 yrs D) 36 yrs
 
Answer & Explanation Answer: B) 34 yrs

Explanation:

Total age of players in team = 22 x 11 = 242
When coach is included, total members = 12, Avg age increases by one becomes 23
Total age when coach is included = 23x12 = 276
Age of coach = 276-242 = 34 yrs.

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Q:

In word, the mailing list is known as the

A) Data source B) Sheet
C) Source D) Data sheet
 
Answer & Explanation Answer: A) Data source

Explanation:

In word, the mailing list is known as the Data source.

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Q:

Assertion(A) : Indus valley people knew the art of navigation.
Reason(R) : Indus valley seals indicate prevalence of overseas trade.

A) R is true but A is fale B) A is true but R is false
C) Both A and R are false D) R correctly explains A
 
Answer & Explanation Answer: D) R correctly explains A

Explanation:

The seals found at Indus valley sites gave evidance of overseas trade, which was possible only with the knowledge of art of navigation.
Thus, both A and R are true & R correctly explains A.

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Q:

A 260 m long train running at the speed of 120 km/hr crosses another train running in opposite direction at the speed of 80 km/hr in 9 sec. What is the length of the other train  ?

A) 240 mts B) 270 mts
C) 260 mts D) 250 mts
 
Answer & Explanation Answer: A) 240 mts

Explanation:

Relative speed = 120 + 80 = 200 km/hr.
= 200 x 5/18 = 500/9 m/sec.

Let the length of the other train be L mts.
Then, (L + 260)/9 = 500/9 => L = 240 mts.

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