The substance you would expect to have a low melting point would be carbon dioxide, so the correct answer would be A
The balanced chemical equation for reaction of
and
is as follows:

From the balanced chemical equation, 2 mol of
reacts with 1 mol of
.
First calculating number of moles of
as follows:

On rearranging,

Here, M is molarity and V is volume. The molarity of
is given 0.274 M or mol/L and volume 155 mL, putting the values,

Since, 1 mol of
reacts with 2 mol of
thus, number of moles of
will be
.
Now, molarity of
is given 0.305 M or mol/L thus, volume can be calculated as follows:

Therefore, volume of
is 278.5 mL.
Answer:
(A) A ball sitting on the ground
Explanation:
D. Not all mixtures are heterogeneous
Physical Properties: Sodium bicarbonate is an odorless, white crystalline solid or fine powder. It has a slightly alkaline taste. Its density is 2.20 g mL-1 and it decomposes in temperatures above 50 ºC. The decomposition yields to sodium carbonate. It is highly soluble in water and poorly soluble in acetone and methanol. It is insoluble in ethanol.
Chemical Properties: Sodium bicarbonate is an amphoteric compounds, it means the compound has a character acids an basic at the same time. It is highly soluble in water, resulting in a slighty alkaline solution.
i hope this part helps i will continue to research on Toothpaste's properties