Answer: 72.41% and 26.90% respectively.
Explanation:
At 60°C, you can dissolve 46.4g of acetanilide in 100mL of ethanol. If you lower the temperature, at 0°C, you can dissolve just 12.8g, which means (46.4g-12.8g)=33.6g of acetanilide must have precipitated from the solution.
We can calculate recovery as:

So the answer to the first question is 72.41%.
For the second part just use the same formula, the mass of the precipitate is the final mass minus the initial mass, (171mg-125mg)=46mg.

So the answer to the second question is 26.90%.
The atomic number of Li is 3
Electron configuration of Li : 1s² 2s¹
The atomic number of Na is 11
Electron configuration of Na : 1s²2s²2p⁶3s¹
Thus there is one electron in the valence shell of Li (2s¹) and that of Na (3s¹). However, the valence electron in Na is in a shell that is farther away from the nucleus compared to that of Li. As a result, the Na valence electron will be held less tightly by the nucleus i.e. it will experience a reduced nuclear attraction and can be removed easily than the Li 2s electron.
Answer:
CH₃CH(CH₃)CH(C₃H₇)CH₂CH(CH₃)₂:
4-isopropyl-2-methylpentane.
Explanation:
Step One: Draw the structure formula of this compound. Parentheses in the formula indicate substitute groups that are connected to the carbon atom to the left.
For example, the first (CH₃) indicates that the second carbon atom from the left is connected to:
- the CH₃- on the left-hand side,
- the -CH(C₃H₇)CH₂CH(CH₃)₂ on the right-hand side,
- a hydrogen atom, and
- an additional CH₃- group that replaced one hydrogen atom.
Each carbon atom in this compound is connected to four other atoms. All bonds between carbon atoms are single bonds.
The C₃H₇ in the second pair of parentheses is the condensed form of CH₃CH₂CH₂-. See the first sketch attached. Groups in parentheses are highlighted.
Step Two: Find the carbon backbone. The backbone of a hydrocarbon is the longest chain of carbon atoms that runs through the compound. See the second sketch attached. The backbone of this compound consists of seven carbon atoms and is highlighted in green. The name for this backbone shall be heptane.
Step Three: Identify and name the substitute groups.
The two substitute groups are circled in blue in the second sketch.
- The one on the right -CH₃ is a methyl group.
- The one on the left is branched.
This group can be formed by removing one hydrogen from the central carbon atom in propane. The name for this group is isopropyl.
Step Four: Number the atoms.
Isopropyl shall be placed before methyl. Start from the right end to minimize the index number on all substitute groups. The methyl group is on carbon number two and the isopropyl group on carbon number four. Hence the name:
4-isopropyl-2-methylheptane.
It shows the atomic number