Answer:
Butan-2-one
Explanation:
1. 1700 cm⁻¹
A strong peak near 1700 cm⁻¹ is almost certainly a carbonyl (C=O) group.
2. Triplet-quartet
A triplet-quartet pattern indicates an ethyl group.
The 2H quartet is a CH₂ adjacent to a CH₃. The peak normally occurs at δ 1.3, but it is shifted 1.2 ppm downfield to δ 2.47 by an adjacent C=O group.
The 3H triplet at δ 1.05 is the methyl group. It, too, is shifted downfield from its normal position at δ 0.9. The effect is smaller, because the methyl group is further from the carbonyl.
3. 3H(s) at δ 2.13
This indicates a CH₃ group with no adjacent hydrogen atoms.
It is shifted 0.8 ppm downfield to δ 2.13 by the adjacent C=O group.
4. Identification
The identified pieces are CH₃CH₂-, -(CO)-, and -CH₃. There is only one way to put them together: CH₃CH₂-(C=O)-CH₃.
The compound is butan-2-one.
Answer : -19.6
Explanation : We can calculate this using the combine equation of boiling point and depression in freezing point and obtain a combined equation which is
∆T(f) = ∆T(b) x {K(f) / K(b)} ;
Where ∆T(f) is depression in freezing point,
∆T(b) is elevation in boiling point,
K(f) is cryoscopic constant for water it is 1.86
K(b) is ebullioscopic constant for water it is 0.512
So we can solve the equation,
∆T(f) = (105.4 -100) X 
= 19.6
So when we have the freezing point depression as 19.6,
we know water freezes at 0° C so the freezing point will be 0 - 19.6 = -19.6 °C
Answer: 8.7 grams
Explanation:
According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number 
of particles.
To calculate the moles, we use the equation:
As oxygen is in excess, Aluminium is the limiting reagent and limits the formation of products.
According to stoichiometry:
4 moles of aluminium give = 2 moles of 
Thus 0.17 moles of aluminium give=
Mass of 
Thus the mass of is 8.7 grams
A. Earth has a magnetic force that is strongest at its core.
