The mass of titanium alloy is 7.01 g
<u><em>calculation</em></u>
Q=mHF
where
Q(heat)= 2960 j
M(mass) = ?
Hf( heat of fusion) = 422.5 j/g
make M the subject of the formula by diving both side of equation by Hf
M=Q/Hf
M= 2960 j/422.5 j/g = 7.01 g
Taking into account the reaction stoichiometry, the correct answer is the third option: 15.63 moles of HgO are needed to produce 250 g of O₂.
In first place, the balanced reaction is:
2 HgO → 2 Hg + O₂
By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:
- HgO: 2 moles
- Hg: 2 moles
- O₂: 1 moles
The molar mass of the compounds is:
- HgO: 216.59 g/mole
- Hg: 200.59 g/mole
- O₂: 32 g/mole
Then, by reaction stoichiometry, the following mass quantities of each compound participate in the reaction:
- HgO: 2 moles× 216.59 g/mole= 433.18 grams
- Hg: 2 moles× 200.59 g/mole= 401.18 grams
- O₂: 1 mole× 32 g/mole= 32 grams
Then the following rule of three can be applied: if by reaction stoichiometry 32 grams of O₂ are produced by 2 moles of HgO, 250 grams of O₂ are produced from how many moles of HgO?

<u><em>moles of HgO= 15.625 moles≅ 15.63 moles</em></u>
Finally, the correct answer is the third option: 15.63 moles of HgO are needed to produce 250 g of O₂.
Learn more about reaction stoichiometry:
Answer:
Chromium, calcium, and osmium
Explanation:
These elements are metals, considering this, these elements electron shells(orbitals) are further away from the nucleus, with this, their attractions are not as strong as non-metals, so some of their electrons are able to move freely.
When you accumulate many atoms, these metals can form a "sea of electrons" because they all have loose electrons interacting with each other. This allows easy conduction of heat and electricity.
The size of this engine in cubic meters is
.
<u>Explanation:</u>
As it is stated that engine size can be measured depending upon the amount of air the cylinders displace, it is also stated that the engine of model Pontiac V8 has a size of 316.6 cubic inches. The problem is to convert the size of engine in cubic meters. We know that 1 inch = 0.0254 m.
Then 
As here the size of engine is 316.6 cubic inches, then in metres it will be

Thus, the size of the engine in cubic meters will be
.
The answer is A because water can only evaporate if a liquid substances becomes gas , in this case it’s the water. When water is heated it evaporates. The molecule moves and vibrates so quickly that they can move to the atmosphere