Tag: chemistry

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Multiple choice 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

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

  1. 63

  2. 80

  3. 93

  4. 102
Reveal answer Fill a bubble to check yourself
A Correct answer
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.
Multiple choice 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

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

  1. $I$
  2. $II$
  3. $III$
  4. $IV$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In Mendeleev's original periodic table, Group I contained the alkali metals and was quite extensive, often holding more elements than other groups in the early versions.

Multiple choice 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

Eka-aluminum and Eka-silicon are known as:

  1. gallium and germanium

  2. aluminium and silicon

  3. iron and sulphur

  4. sodium and silicon
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Answer A

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

Multiple choice 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

The Mendeleev's periodic table consists of groups: 

  1. seven

  2. eight

  3. nine

  4. ten
Reveal answer Fill a bubble to check yourself
B Correct answer
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.
Multiple choice 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

Which element was named Eka-aluminium by Mendeleev?

  1. Scandium

  2. Gallium

  3. Germanium

  4. Indium
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Mendeleev predicted the existence of several elements, naming them based on their position relative to known elements. Eka-aluminium was his name for the element that would later be discovered as Gallium.

Multiple choice 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

The basis of periodic law presented by Mendeleev was: 

  1. valency

  2. atomic mass

  3. atomic number

  4. atomic volume
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

In solid state N2O5 exits as:

  1. $[NO3]^ - [NO2]^+$
  2. $[NO2]^ - [NO3]^ +$
  3. $[N2O4]^ + O^-$
  4. $[NO3] [NO2]$
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

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

  1. fertilizer

  2. dehydrating agent

  3. oxidising agent

  4. reducing agent
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

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