Answer:
7.32g of HNO3 are required.
Explanation:
1st) From the balanced reaction we know that 2 moles of HNO3 react with 1 mole of Ca(OH)2 to produce 2 moles of H2O and 1 mole of Ca(NO3)2.
From this, we find that the relation between HNO3 and Ca(OH)2 is that 2 moles of HNO3 react with 1 mole of Ca(OH)2.
2nd) This is the order of the relations that we have to use in the equation to calculate the grams of nitric acid:
• starting with the 4.30 grams of Ca(OH)2.
,
• using the molar mass of Ca(OH)2 (74g/mol).
,
• relation of the 2 moles of HNO3 that react with 1 mole of Ca(OH)2 .
,
• using the molar mass of HNO3 (63.02g/mol).

So, 7.32g of HNO3 are required.
Answer:
Substances 1 and 2
Explanation:
an element only has 1 kind of atoms :3
Answer:
The answer is option 3, C5H12 + 8O2 → 5CO2 + 6H2O.
Explanation:
In an exothermic reaction, the energy change(ΔH) will always be a negative value.
For endothermic reaction, the energy change's value is positive.
In the options above, option 1 and 2 are endothermic reaction.
Answer: 69.72 kg of cryolite will be produced.
Explanation:
The balanced chemical equation is:

To calculate the moles, we use the equation:

moles of
= 
moles of
= 
moles of
= 
As 1 mole of
reacts with 6 moles of 
166 moles of
reacts with =
moles of 
As 1 mole of
reacts with 12 moles of 
166 moles of
reacts with =
moles of 
Thus
is the limiting reagent.
As 1 mole of
produces = 2 moles of cryolite
166 moles of
reacts with =
moles of cryolite
Mass of cryolite
= 
Thus 69.72 kg of cryolite will be produced.
A) acids because they start with h