1. 2Pb(NO₃)₂ → 2PbO + 4NO₂ + O₂
2. CH₄ + 2O₂ → CO₂ + 2H₂O
3. Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag
4. MnO₂ + 4HCl → MnCl₂ + 2H₂O + Cl₂
5. Pb(NO₃)₂ + 2NaCl → PbCl₂ + 2NaNO₃
1)

2)
CuSO_4+Cu_2Cl_2\neq>

Answer:
The correct answer is C.
Explanation:
To solve this problem, we should first recall possible units for mass and volume. Mass can be represented with units of grams, kilograms, etc. Volume has units of cubic meters, cubic centimeters, etc.
Therefore, since we know that density is mass divided by volume, the only answer that makes sense here is C. grams per cubic centimeter (where per signifies that grams are being divided by cubic centimeters).
Hope this helps!
Since the number of moles of a substance is the mass divided by the molar mass of the substance, we can just simply multiply the molar mass of magnesium chloride by the number of moles, which is 4.40 in this case.
To find the molar mass, refer to the periodic table for the relative atomic mass of Mg and Cl and add them together. Since there’s 2 chloride ions in MgCl2, double the relative atomic mass of Cl when adding.
24.31 + 35.45x2
=95.21
Now just multiply 95.21 to 4.40mol, which you’ll get 418.9g (corrected to 3 significant figures)
It is opaque because you can't see anything on the other side of the apple.
An apple is red because of the frequency of light shining on it makes it seem that it is red, as it is reflected. It seems it is red because it reflects infrared waves.