Answer:- 448 mL of hydrogen gas are formed.
Solution:- It asks to calculate the volume of hydrogen gas formed in milliliters at STP when 0.020 moles of magnesium reacts with excess HCl acid. The balanced equation is:

There is 1:1 mol ratio between Mg and hydrogen gas. So, the moles of hydrogen gas is also equals to the moles of Mg reacted.
moles of Hydrogen gas formed = 0.020 mol
At STP, volume of 1 mol of the gas is 22.4 L. We need to calculate the volume of 0.02 moles of hydrogen gas.

= 0.448 L
They want answer in mL. So, let's convert L to mL using the conversion formula, 1L = 1000mL

= 448 mL
So, 0.020 moles of magnesium would produce 448 mL of hydrogen gas at STP on reacting with excess of HCl acid.
.answer:
so the first one is analogous
the second is homologous
and the third is analogous
explanation:
analogous. this means they share a similar function (flight) but do not have the same embryonic origin.
Answer:
17,890 J
Explanation:
The amount of heat released by a gaseous substance when it condenses is given by the formula

where
n is the number of moles of the substance
is the latent heat of vaporization
The formula can be applied if the substance is at its vaporization temperature.
In this problem, we have:
n = 0.440 mol is the number of moles of steam
is the latent heat of vaporization of water
And the steam is already at 100C, so we can apply the formula:

1. Dry Ice (solid carbon dioxide)
2. Iodine
3. Arsenic
4. Naphthalene
Answer:
Mole of the H2O = 4.5
Number of molecules =4.5 multipled by avogadro's number.