Solutions

Two solutions are isotonic if they have same molar concentrations of particles in solution.
0.1 M = 0.3 M ion concentration
0.1 M = 0.3 M ion concentration

Step 1: Understanding pKa.
The pKa value of a compound gives insight into its acidity. The lower the pKa, the stronger the acid. In this case, we are asked to identify the compound with the correct pKa value.
Step 2: Analyzing the Options.
- (A) is the correct compound as it is a simple carboxylic acid, and its pKa is approximately 4.8.
- (B) is a carboxylic acid, but the electron-withdrawing chlorine group will lower the pKa slightly, making it more acidic than acetic acid.
- (C) is a benzoic acid derivative, which has a slightly lower pKa than acetic acid.
- (D) is formic acid, which has a lower pKa (~3.75), indicating a stronger acid than acetic acid.
Step 3: Conclusion.
The correct answer is (A) as it has the pKa value closest to 4.8, typical for acetic acid.

Step 1: Understanding the Problem.
We are asked to calculate the weight percentage (W/W) of NaOH in a solution. The formula for weight percentage is:
Step 2: Calculation.
- Molar mass of NaOH = 40 g/mol.
- Amount of NaOH = . Therefore, the weight of NaOH = .
- The weight of water = 22 g.
- The total weight of the solution = .
Step 3: Conclusion.
The correct answer is (A) 35.71% W/W.

Step 1: Understanding the Question.
The question asks about the bonding type involved in the structure of proteins. Proteins are made of amino acids linked by covalent bonds.
Step 2: Analyzing the Options.
- (A) Covalent bonding is correct because amino acids are connected by peptide bonds, a type of covalent bond.
- (B) Ionic bonding is not the main type of bonding in proteins.
- (C) Hydrogen bonding plays a role in protein folding but is not the primary bonding type.
- (D) Van der Waals forces are weak and also contribute to protein structure but are not the main force.
Step 3: Conclusion.
The correct answer is (A) Covalent bonding.

Step 1: Understanding the Question.
RNA (ribonucleic acid) contains a sugar molecule that is crucial for its structure. This sugar is different from the sugar found in DNA.
Step 2: Analyzing the Options.
- (A) Ribose is the sugar present in RNA, and it has a hydroxyl group (-OH) at the 2' carbon.
- (B) Deoxyribose is the sugar found in DNA, where the 2' carbon lacks the hydroxyl group.
- (C) Glucose is not the sugar used in RNA or DNA.
- (D) Fructose is not the sugar in RNA.
Step 3: Conclusion.
The correct answer is (A) Ribose.