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.
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Answer:
Chemical reactions that take place inside living things are called biochemical reactions. The sum of all the biochemical reactions in an organism is referred to as metabolism. Metabolism includes both exothermic (heat-releasing) chemical reactions and endothermic (heat-absorbing) chemical reactions.
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Beta radiation / decay would likely occur when the ratio of protons to neutrons is below the band of stability.
Answer:
315.51g/mol
Explanation:
137(33 + (16.00 + 1.01) 2 + 8 [1.01 (2) + 16.00] = 315.51g/mol
Mention four reasons why the poll ordinance failed