Molar mass helium gas :
He = 4.0 g/mol
number of moles: 3.75 / 4.0 => 0.9375 moles
1 mole ------ 22.4 ( at STP)
0.9375 ------ ?
volume = 0.9375 x 22.4 / 1
Volume = 21 / 1
Volume = 21 L
hope this helps!
B obviously not a or c so if it aint b its D
These could all go either way, hardness and other special properties are what I'm guessing would be the most accurate in determining the kind of material.
luster, cleavage, streak, and color can all be affected by other factors. but I guess cleavage would also be accurate. so I guess hardness special properties and cleavage would be the most reliable.
Answer:
1.67 moles
Explanation:
From the balanced equation of reaction:

1 mole of sulfur dioxide, SO2, is required to produce 3 moles of sulfur, S.
<em>If 1 mole SO2 = 3 moles S, then, how many moles of SO2 would be required for 5 moles S?</em>
Moles of SO2 needed = 5 x 1/3
= 5/3 or 1.67 moles
Hence, <u>1.67 moles of SO2 would be required to produce 5.0 moles of S.</u>
1. b
2.a
3.c
I think . hope I get it right