Question 1
100 mL of 0.20 mol L⁻¹ aqueous ammonia is mixed with 50 mL of 0.30 mol L⁻¹ HCl at 298 K. What is the pH of the mixture? (pKb of NH₃ = 4.74; pKw = 14.00; log 2 = 0.30; log 3 = 0.48.)
How to answer NEET assertion-reason and statement questions
Judge each statement on its own first, then the link. In assertion-reason, the reason must give the cause of the assertion, not just another true fact. In a statement pair, mark each statement true or false before you look at the options.
| Assertion-reason | Is A true? Is R true? Does R explain A? |
|---|---|
| Statement I and II | Four patterns: both true, both false, or one of each |
| How many correct | Mark every statement, then count |
| Match the lists | Fix the pairs you are sure of, then eliminate |
Assertion-reason in three checks
- Check the assertion alone: true or false on the textbook account.
- Check the reason alone, in the same way.
- Only if both are true, ask whether the reason is why the assertion happens. A reason that is true but about something else does not explain it.
Statement and count questions
Write T or F beside each statement before reading the options. Most errors come from reading the options first and then bending a statement to fit one. In a how-many question, a single statement misjudged changes the answer, so check the one you are least sure of twice.
Match the following
Start from the pair you are surest of and strike out every option that does not contain it. Two sure pairs usually leave one option.
Try 2 questions
Question 2
A chromium(III) complex has the composition CrCl₃·6H₂O (molar mass 266.5 g/mol), and chromium has coordination number 6 in it. A solution of 2.665 g of the complex gives 2.87 g of AgCl at once with excess silver nitrate. What is the freezing point depression of a 0.10 mol kg⁻¹ aqueous solution of this complex, assuming complete dissociation? (AgCl 143.5 g/mol; Kf of water 1.86 K kg mol⁻¹.)
Next step
Questions people ask
What if the assertion is false?
Then the answer is whichever option says the assertion is false, with the reason judged on its own. Whether the reason explains the assertion no longer matters.