Tag: properties of alkaline earth metals

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Multiple choice chemistry group 2 physical properties of alkaline earth metals alkali metals properties of alkaline earth metals

Select the correct statement out of the following.

  1. calcium fluoride is soluble in water.

  2. barium sulfate is soluble in water.

  3. barium dioxide is soluble in water.

  4. magnesium sulfate is soluble in water.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Magnesium sulfate is highly soluble in water (Epsom salt). Calcium fluoride and barium sulfate are notoriously insoluble in water.

Multiple choice chemistry group 2 physical properties of alkaline earth metals alkali metals properties of alkaline earth metals

The sulphate of which metal given below has the highest solubility in water?

  1. $Ca$
  2. $Ba$
  3. $Sr$
  4. $Mg$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

On moving down the group of alkaline earth metals, the solubility of metal sulphates decreases. Also, the ionic size increases and hydration energy of metal ion decreases. Hence, magnesium sulphate($MgSO _4$) has lowest solubility.

Multiple choice chemistry group 2 physical properties of alkaline earth metals alkali metals properties of alkaline earth metals

Which of the following salt gives a crimson red colour in flame test?

  1. $BaCl _{2}$
  2. $CaCl _{2}$
  3. $BeCl _{2}$
  4. $SrCl _{2}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Strontium chloride($SrCl _2$) gives crimson red colour in the flame test. It is due to the excitation of electrons by the thermal energy, which is then followed by de-excitation of electron to ground state along with liberation of light in the visible range.

Multiple choice chemistry group 2 physical properties of alkaline earth metals alkali metals properties of alkaline earth metals

Assertion(A) : Beryllium and magnesium do not impart characteristic colour in flame.
Reasoning(R) : Both Beryllium and magnesium have high I.E.

  1. Both Assertion and Reason are true and Reason is the correct explanation of Assertion

  2. Both Assertion and Reason are true but Reason is not a correct explanation of Assertion

  3. Assertion is true but Reason is false

  4. Both Assertion and Reason are false
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Small sized Be and Mg atoms have high ionization energies. Hence, the energy of flame is not sufficient to excite their electrons. Thus, Be and Mg do not produce colour in flame.

Multiple choice chemistry group 2 physical properties of alkaline earth metals alkali metals properties of alkaline earth metals

Alkaline earth metal(s) which does (do) not
impart colour to the flame is (are):

  1. Be

  2. Mg

  3. Ca

  4. Sr
Reveal answer Fill a bubble to check yourself
A,B Correct answer
Explanation

Beryllium($Be$) and magnesium($Mg$) cannot give flame test. They have small size. They strongly binds their electrons. Thus they have high ionization enthalpies. The thermal energy of flame is not sufficient to excites their electrons.

Multiple choice chemistry group 2 physical properties of alkaline earth metals alkali metals properties of alkaline earth metals

Which of the following shows least melting point?

  1. $Be$
  2. $Mg$
  3. $Ca$
  4. $Sr$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Ans : $B$ $\rightarrow$ $Mg$

Generally melting point of the metals decreases down the group. But $Mg$ has anomalously low melting point in group $2$.
Group $2$ metals have metallic bonding. If we look at the crystal structure, $Be$ & $Mg$ are hexagonal close packed, $Ca$ & $Sr$ are face centered cubic.
At melting point, $Be$, $Ca$ and $Sr$ are body centered where as $Mg$ is hexagonal closed packed. Due to this arrangement, $Mg$ shows least melting point