Tag: alkali metals

Questions Related to alkali metals

Which of the following alkali metal(s) form complex hydrides?

chemistry patterns and properties of metals periodic trends in chemical properties alkali metals study of specific groups

  1. Li

  2. K

  3. Na

  4. Rb

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Correct Option: A,C
Explanation:

Lithium and sodium form complex hydrides such as lithium aluminium hydride and sodium borohydride.

Which of the following reacts most vigorously with water?

chemistry elements of group 1 and group 2 periodic trends in chemical properties alkali metals study of specific groups

  1. Alkali metal

  2. Alkaline earth metal

  3. Transition metal

  4. Halogen

  5. Noble gas

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Correct Option: A
Explanation:

Answer(A)
Alkali metals react most vigorously with water.

Radium is a harmful element which emits radiation.

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

  1. True

  2. False

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Correct Option: A
Explanation:

Radium is a radioactive element. The radiations cause harms to humans on exposure.

Hence, it is true that Radium is a harmful element which emits radiations.

Select the correct statement out of the following.

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

  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.

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Correct Option: D

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

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

  1. $Ca$

  2. $Ba$

  3. $Sr$

  4. $Mg$

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Correct Option: D
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.

Which of the following metals cannot give flame
tests?

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

  1. Be

  2. Na

  3. K

  4. Ca

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Correct Option: A
Explanation:

Beryllium cannot give flame test. Beryllium has small size. It strongly binds its electrons. Thus it has high ionization enthalpy. The thermal energy of flame is not sufficient to excite its electrons.

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

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

  1. $BaCl _{2}$

  2. $CaCl _{2}$

  3. $BeCl _{2}$

  4. $SrCl _{2}$

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Correct Option: D
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.

Passivity is exhibited by: $A) Be , B) Mg, C) Al ,D) B$

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

  1. $A, B$

  2. $B, C$

  3. $A, C$

  4. $B, D$

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Correct Option: C
Explanation:

Action of oxidizing agents such as conc. nitric acid forms a layer of an oxide on the surface of Be and Al. Hence these metals become passive and do not react.

Sulphate of an alkaline earth metal which crystalizes without water of hydration is?

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

  1. $Be^{2+}$

  2. $Mg^{2+}$

  3. $Ca^{2+}$

  4. $Sr^{2+}$

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Correct Option: D
Explanation:

Strontium sulphate crystalizes without water of hydration.

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

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

  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

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Correct Option: A
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.