As we move down the group, the metallic bond becomes more stable and the formation of forming covalent bond decreases down the group due to the large size of elements.
Covalent and metallic bonding leads to higher melting points. Due to a decrease in attractive forces from carbon to lead there is a drop in melting point.
Carbon forms large covalent molecules than silicon and hence has a higher melting point than silicon.
Similarly, Ge also forms a large number of covalent bonds and has a smaller size as compared to that of Sn. Hence melting point decreases from Ge to Sn.
The order will be C>Si>Ge>Pb>Sn.
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A. NO2 because the elements are both nonmetals.
The Giant-Impact theory. People basically believed that the moon was created from the collision between earth and another small planet:)
I believe the answer is C
PH = -log [H+]
pH = -log (1.0x10^-4) = -(-4) = 4 or A
