Tag: chemistry

Questions Related to chemistry

The chemical formula of the compound containing carbon and chlorine is:

chemistry atoms, molecules and radicals molecular formula and valency valency and chemical formulae combining capacity and chemical formulae

  1. $CCl _2$

  2. $CCl _3$

  3. $CCl _4$

  4. $C _2Cl _4$

Show answer
Correct Option: C
Explanation:

Carbon has a valency of$ +4$ and chlorine has a valency equal to $-1. $Compound is Carbon tetrachloride $CCl _4$.

Predict the formulae of the binary compounds formed by combination of the following pairs of elements:
(i)    Magnesium and nitrogen
(ii)   Silicon and oxygen

chemistry atoms, molecules and radicals molecular formula and valency valency and chemical formulae combining capacity and chemical formulae

  1. $MgN _{2}, SiO _{2}$

  2. $Mg _{3}N _{2}, SiO _{2}$

  3. $Mg _{2}N _{3}, Si _{2}O _{3}$

  4. $MgN, SiO _{2}$

Show answer
Correct Option: B
Explanation:

Three Mg ( $+2$ oxidation state) combine with two N ($-3$ oxidation state) to form $Mg _3N _2$.

One Si ( $+4$ oxidation state) combine with two O ($-2$ oxidation state) to form $SiO _2$.

Note: In a neutral molecule, the total charge on cations is numerically equal to the total charge on anions.

Predict the formula of stable compound formed by an element with atomic number 114 and fluorine.

chemistry atoms, molecules and radicals molecular formula and valency valency and chemical formulae combining capacity and chemical formulae

  1. $AF _{3}$

  2. $AF _{2}$

  3. $AF$

  4. $AF _{4}$

Show answer
Correct Option: D
Explanation:
Element A with atomic number 114 will share four electrons to attain stable noble gas electronic configuration. It falls in the Carbon family.

Fluorine shares one electron to attain stable noble gas electronic configuration. One atom of A combines with four atoms of F to form $AF _4$.

Hence, the correct option is $\text{D}$

A gas is heated through 1°C in a closed vessel and so the pressure increases by 0.4%. The initial temperature of the gas was

chemistry atoms, molecules and radicals molecular formula and valency valency and chemical formulae combining capacity and chemical formulae

  1. $-23^0C$

  2. $23^0C$

  3. $250^0C$

  4. $523^0C$

Show answer
Correct Option: A
Explanation:

Law of octaves stated :

chemistry the periodic table newland's law of octaves development of the modern periodic table into the history

  1. every eighth element had properties similar to the first element

  2. every third element had properties similar to the first element

  3. the properties of the middle element were in between the other two members

  4. the properties of the elements were repeated after regular intervals of 3,4 or 8 elements

Show answer
Correct Option: A
Explanation:

Newland's Law of octaves stated that if elements (known at Newland's time) were arranged in increasing order of their atomic weights, every eighth element had properties similar to the first element. For example, Li and Na have similar properties.

What were the limitations of Newlands' classification?

chemistry the periodic table newland's law of octaves development of the modern periodic table into the history

  1. It was applicable only for lighter elements

  2. He adjusted two elements on the same place

  3. The pattern was only observed up to calcium

  4. All of the above

Show answer
Correct Option: D
Explanation:

The limitations of Newlands' classification were:

  • It was only applicable for lighter elements.
  • He adjusted two elements in one place.
  • The pattern was only observed up to calcium.

Newlands' law of octaves worked well only with :

chemistry the periodic table newland's law of octaves development of the modern periodic table into the history

  1. heavier elements

  2. lighter elements

  3. Both A and B

  4. Neither A nor B

Show answer
Correct Option: B
Explanation:

Newlands' law of octaves worked well with lighter elements only. As the weight is increased, the pattern started changing and was no longer following the law.

The placement of elements in the Newlands' table was compared to :

chemistry the periodic table newland's law of octaves development of the modern periodic table into the history

  1. weeks of a month

  2. notes of music

  3. months of a year

  4. days of a month

Show answer
Correct Option: B
Explanation:

The placement of elements in the Newlands' periodic table was compared to the notes of music where the first note and the eighth note are same. Similarly, in Newlands' periodic table, the chemical properties also repeat after $7$ elements.

In Newlands' table, which of the following elements was not placed in the same group in which cobalt and nickel were present?

chemistry the periodic table newland's law of octaves development of the modern periodic table into the history

  1. Chlorine

  2. Bromine

  3. Fluorine

  4. None of the above

Show answer
Correct Option: D
Explanation:

In Newlands' table, chlorine, bromine and fluorine were placed in the same group in which cobalt and nickel were present.

If X and Y are two elements which belong to same group of Newland's periodic table, how many elements exists between X and Y?

chemistry the periodic table newland's law of octaves development of the modern periodic table into the history

  1. $4$

  2. $5$

  3. $6$

  4. $7$

Show answer
Correct Option: C
Explanation:

In Newland's periodic table, $1$st element and the $8$th element have the same chemical property, i.e., they belong to the same group. So, the table will look like:
$\begin{equation}X\;1\;2\;3\;4\;5\;6 \ Y\end{equation}$
So, there are $6$ elements between X and Y.