Multiple Choice QuestionsWhich one of the following bonds produces a solid that reflects light in the visible region and whose electrical conductivity decreases with temperature and hs high melting point?
metallic bonding
van der Waal's bonding
Ionic bonding
Ionic bonding
A.
metallic bonding
Metallic bonding is formed due to the attraction of valence (free) electrons with the positive ion cores. Their conductivity decreases with rising of temperature. When visible light falls on a metallic crystal, the electrons of atoms absorb visible light, so they are opaque to visible light. However, some orbital electrons absorb energy and reach to an excited state. They then return to their normal state, remitting light of the same frequency.
If the lattice parameter for a crystalline structure is 3.6 A, then atomic radius in fcc crystal is
1.18 A
2.10 A
2.92 A
2.92 A
Assertion: Unlike electric force and gravitational forces, nuclear force has limited range.
Reason: Nuclear force do not obey inverse square law.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
Assertion: The Coulomb force is dominating force in the universe.
Reason: The Coulomb force is weaker than the gravitational force.
if both assertion and reason are true and the reason is the correct explanation of the assertion
if both assertion and reason are true and the reason is not the correct explanation of the assertion
if assertion is true but reason is false
if both assertion and reason are false statements
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