Answer:
(3) NaNO₃
Step-by-step explanation:
Sodium nitrate has ionic bonds, because it consists of Na⁺ and NO₃⁻ ions.
However, the nitrate ions have <em>covalent bonds</em> between the O atoms and the central N atoms.
(1) and (2) are <em>wrong</em>. Both N₂O₅ and HCl consist of nonmetals, so they are <em>covalent</em> compounds.
(4) is <em>wrong</em>. NaCl has <em>only ionic bonds</em> between the Na⁺ and Cl⁻ ions
Separation of components of crude oil
Answer : The molecular weight of a substance is 157.3 g/mol
Explanation :
As we are given that 7 % by weight that means 7 grams of solute present in 100 grams of solution.
Mass of solute = 7 g
Mass of solution = 100 g
Mass of solvent = 100 - 7 = 93 g
Formula used :

where,
= change in freezing point
= temperature of pure water = 
= temperature of solution = 
= freezing point constant of water = 
m = molality
Now put all the given values in this formula, we get


Therefore, the molecular weight of a substance is 157.3 g/mol
Answer:
Mass = Number of neutrons + Atomic number (aka number of protons)
Explanation:
ΔΗ= -115.6 kJ/mol
H2 has a Mr of 2, so as mol=mass/mr we can work out that there are 4 moles of H reacting
Therefore we multiply -115.6 by 4 = -462.4