Sawaal
106
Q:

Boron cannot form which one of the following anions?

(1) BO2-

(2) BF63-

(3) BH4-

(4) B(OH)4-

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

Answer:   B) Option 2



Explanation:

Due to absence of low lying vacant d orbital in B, sp3d2hybridization is not possible hence BF63-will not formed. 

Subject: Chemistry
Exam Prep: AIEEE
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An element which is preserved under water is 

A) sodium B) sulphur
C) red phosphorus D) white phosphorus
 
Answer & Explanation Answer: D) white phosphorus

Explanation:

White phosphorus undergoes spontaneous combustion when exposed to air. In order to prevent this spontaneous ignition, it is preserved under water. 

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27 9232
Q:

Which of the following is called 'the King of Chemicals' ?

A) Nitric acid B) Hydrochloric acid
C) Silver nitrate D) Sulphuric acid
 
Answer & Explanation Answer: D) Sulphuric acid

Explanation:

Sulphuric acid is called the King of Chemicals because it is used in the preparation of a very large number of other useful chemicals such as hydrochloric acid, nitric acid, dyes, drugs etc. In fact the annual production of shulpuric acid in a country is a measure of the economy of the country.

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9 8426
Q:

According to the modern Periodic Law, the properties of elements are periodic functions of their

A) volency B) atomic mass
C) number of neutrons D) atomic number
 
Answer & Explanation Answer: D) atomic number

Explanation:

Atomic number is the serial number of an element in the periodic classification of elements. It gives the number of protons and also the number of electrons in an atom.

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6 5099
Q:

Washing soda is 

A) sodium hydroxide B) sodium carbonate
C) sodium bicorbonate D) Potassium chloride
 
Answer & Explanation Answer: B) sodium carbonate

Explanation:

Sodium hydroxide - NaOH is caustic soda

 

Sodium carbonate - Na2CO3 is washing soda

 

Sodium bicarbonate - NaHCO3  is baking soda 

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7 4998
Q:

The enzyme in whosepresence glucose and fructose are converted into alcohol is 

A) Diastase B) Maltase
C) Invertase D) Zymase
 
Answer & Explanation Answer: D) Zymase

Explanation:
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1 2409
Q:

When formaldehyde and potassium hydroxide are heated , we get 

A) Acetylene B) Methyl alcohol
C) Methane D) Ethyl formate
 
Answer & Explanation Answer: B) Methyl alcohol

Explanation:
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147 24329
Q:

The atoms of the elements having same atomic number but different mass number are called

A) Isobar B) Isotopes
C) Iso electronic D) Isotones
 
Answer & Explanation Answer: B) Isotopes

Explanation:
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4 3297
Q:

An atom has 7 electrons in its M - shell and contains 18 neutrons in its nucleus. What is its mass number

A) 25 B) 27
C) 35 D) 43
 
Answer & Explanation Answer: C) 35

Explanation:

According to Bohr model, Each shell can occupy 2n2 electrons in their orbits where n=1,2,3.. for K,L,M,..

 

The atom has 2 electrons in k, 8 electrons in L and 7 electrons in M = 2 + 8 + 7 = 17

 

And given that its nucleus has 18 neutrons

 

=> its mass number = number of (electrons + neutrons ) = 17 + 18 = 35

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45 9685