Which of the following statements is true? i. carbon forms covalent rather than ionic bonds. ii. carbon has an electronegativity value that is midway between that of the most metallic element and the most nonmetallic element. iii. carbon forms four bonds in virtually all its compounds. iv. a si-si bond is much stronger than a c-c bond. v. relatively little heat is released when a c chain reacts and one bond replaces the other.

Carbon in reality forms covalent bonds rather than ionic bond, because it has four electrons in its valence shell and needs 4 electron to complete its octet, therefore it don't form ionic bonds. Therefore, this statement is true.Carbon is placed in p-block, and has an atomic number 6, it has electronegativity between metals and non-metals. Therefore, this statement is correct.Carbon forms four bonds because in the excited it has four unpaired electron, hence this statement is true.Silicon is below carbon in periodic table, its size is larger than carbon therefore the bond between Si-Si will be weaker in comparison to the bond between Carbon-Carbon.

Temperature and pressure