Hi,
The first answer is B. Ammonia has a pH value more than 7 and lemon juice has a pH value less than 7, as ammonia is a base and lemon juice is acid.
The second answer is A. Highly basic, as sodium hydroxide is a strong base.
The third answer is A. 5, since acids have a pH value less than 7.
The fourth answer is C. It is acidic, because carbon dioxide is soluble in water so the water's pH value decreases as carbon dioxide has a pH value less than 7.
