Chemistry competition

A solution is prepared by dissolving 9.8g of H₂SO₄ (Molar Mass = 98 g/mol) in enough water to make 250mL of solution. What is the molarity of the solution?

• 0.2M

• 0.4M

• 0.5M

• 0.0M

Which of the following statements about dilution is correct?

• The dilution formula only works for acids, not bases.

• The number of moles of solute remains constant before and after dilution.

• Adding water increases both the moles of solute and molarity.

• Doubling the volume of a solution doubles its molarity.

Which gas is responsible for the characteristic smell of rotten eggs?

• Ammonia (NH₃)

• Hydrogen sulfide (H₂S)

• Carbon monoxide (CO)

• Sulfur dioxide (SO₂)

A 1.500g sample of an unknown sulfate compound is analyzed gravimetrically. It produces 3.250g of BaSO₄ (Molar Mass = 233.39 g/mol). What is the % sulfate (SO₄²⁻) in the original sample?

• 12.1%

• 28.0%

• 43.2%
  

• 56.8%

Which of the following solutions has the lowest pH?

• 0.1 M NaOH

• 0.1 M HCl

• 0.1 M NH₃

• 1.0 M HCl

What is the oxidation state of chromium in potassium dichromate (K₂Cr₂O₇)?

• +2

• +3

• +6

• +7

Which of the following best describes why Bohr’s model fails for multi-electron

• It does not include quantized energy levels.

• It assumes electrons orbit the nucleus in fixed paths.

• It correctly predicts spectral lines for all elements.

• It accounts for electron repulsions and complex interactions.

Which of the following compounds will exhibit hydrogen bonding?

• CH₄

• CO₂

• NH₃

• CCl₄

Can two solutions with the same molarity have different numbers of moles of solute?

• Yes

• No

Does the Bohr model correctly predict the energy levels of the hydrogen-like He⁺ ion?

• Yes

• No