Tag: chemistry

Questions Related to chemistry

How many elements were known when Mendeleev presented the periodic table?

chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

  1. 63

  2. 80

  3. 93

  4. 102

Show answer
Correct Option: A
Explanation:
63 elements were known during the time of the introduction of the Mendeleev periodic table.

During Mendeleev's work, only 63 elements were known.

Option A is correct.

Mark the group which has maximum number of element in Mendeleev's periodic table:

chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

  1. $I$

  2. $II$

  3. $III$

  4. $IV$

Show answer
Correct Option: A

Eka-aluminum and Eka-silicon are known as:

chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

  1. gallium and germanium

  2. aluminium and silicon

  3. iron and sulphur

  4. sodium and silicon

Show answer
Correct Option: A
Explanation:

Answer A

According to Mendeleev he named eka aluminium presently known as Gallium
and eka silicon presently known as Germanium.

The Mendeleev's periodic table consists of groups: 

chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

  1. seven

  2. eight

  3. nine

  4. ten

Show answer
Correct Option: B
Explanation:
Eight groups were there in the Mendeleev's periodic table.

Mendeleev divided his periodic table in eight groups and seven periods.

Option B is correct.

Which element was named Eka-aluminium by Mendeleev?

chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

  1. Scandium

  2. Gallium

  3. Germanium

  4. Indium

Show answer
Correct Option: B

The basis of periodic law presented by Mendeleev was: 

chemistry the periodic table mendeleef's periodic table mendeleev's periodic law and its limitations mendeleev's periodic table development of the modern periodic table into the history

  1. valency

  2. atomic mass

  3. atomic number

  4. atomic volume

Show answer
Correct Option: B
Explanation:

He grouped the elements with similar properties and observed that elements were arranged in the increasing order of atomic mass and there was the periodic occurrence of elements with similar properties.

According to this observation, he formulated a periodic law which states:

“the properties of elements are the periodic function of their atomic masses.”

Option B is correct.

The symbol of $Na$ represents the element:

chemistry stoichiometry matter: states, classification and properties look, learn and experience study of matter

  1. nitrogen

  2. nickel

  3. sodium

  4. potassium

Show answer
Correct Option: C
Explanation:

$Na$ represents the symbol of sodium.


Sodium is a chemical element with atomic number 11. It is a soft, silvery-white, highly reactive metal.

Classification means ____ of things.

chemistry stoichiometry matter: states, classification and properties look, learn and experience study of matter

  1. dividing

  2. grouping

  3. removal

  4. none of these

Show answer
Correct Option: B
Explanation:

Classification of things means a grouping of things with similar properties together.

In solid state N2O5 exits as:

chemistry nitrogen and sulfur nitrogen gas component of air - nitrogen nitrogen

  1. $[NO3]^ - [NO2]^+$

  2. $[NO2]^ - [NO3]^ +$

  3. $[N2O4]^ + O^-$

  4. $[NO3] [NO2]$

Show answer
Correct Option: A
Explanation:

Solid $N _2O _5$ is a salt, consisting of separated anions and cations. The cation is the linear nitronium ion $NO _2^+$ and the anion is the planar nitrate $NO _3^−$ ion. Thus, the solid could be called nitronium nitrate. Both nitrogen centers have oxidation state +5.

$\displaystyle Ca+C _{2} \rightarrow CaC _{2}\xrightarrow{N _{2}}A$
Compound ( A ) is used as a / an :

chemistry nitrogen and sulfur nitrogen gas component of air - nitrogen nitrogen

  1. fertilizer

  2. dehydrating agent

  3. oxidising agent

  4. reducing agent

Show answer
Correct Option: A
Explanation:

Calcium carbide reacts with nitrogen at high temperature to form calcium cyanamide which is used as fertilizer.
$\displaystyle Ca+C _{2} \rightarrow CaC _{2}\xrightarrow{N _{2}}CaCN _2 + C$