The melting point of potassium = 
Melting point of titanium = 
Titanium has a stronger metallic bonding compared to potassium. Titanium being a transition metal has greater number of valence electrons (4 valence electrons) contributing to the valence electron sea compared to potassium which has only one valence electron. The atomic size of Titanium much lower than that of potassium, so the bonding between Titanium atoms is stronger than that of potassium. Hence, the melting point of Titanium is much higher than that of potassium.
It is called convection. When warm air, or current, moves up and disperse outwards as cold air, or current, moves into the warmer region.
Answer to the Question
C. Barium phosphate
<u>Answer:</u> The correct answer is standard reduction potential
<u>Explanation:</u>
Oxidation reaction is defined as the reaction in which an atom looses its electrons. The oxidation number of the atom gets increased during this reaction.
Reduction reaction is defined as the reaction in which an atom gains electrons. The oxidation number of the atom gets reduced during this reaction.
Standard reduction potential is defined as the tendency of a chemical substance to get reduced. It is denoted as 
The substance having highest positive potential will always get reduced and will undergo reduction reaction.
Hence, the correct answer is standard reduction potential
