Online Test Term 1 STPM

Which combination shows the correct number of electrons and neutrons of the respective species?

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Ammonia burns in oxygen according to the equation given in the diagram.

100cm³ of ammonia is burnt in 100cm³ of oxygen. What is the volume of oxygen remaining?

• 25cm³

• 50 cm³

• 75 cm³

• 80 cm³

1. The energy difference between the second energy level and the third level of hydrogen atom is 3.03 x 10^-19 J. What is the frequency of the emitted light when an electronic transition takes place between the two levels?

• 3.03 x 10^-19 Hz

• 4.57 x 10¹⁴ Hz

• 3.29 x 10¹⁵ Hz

• 6.02 x 10²³ Hz

An electron in the second shell of an atom can occupy what type of orbital?

• The orbital closest to the nucleus

• An s orbital

• A p orbital

• Either an s or p orbital

In which of the following compounds, hydrogen exists as the H^– ion?

• NaH

• AlH₃

• SiH₄

• PH₃

Which of the following substances does not contain a coordinate bond?

• Ammonia molecule, NH₃

• Ammonium ion, NH₄⁺

• Hydroxonium ion, H₃O⁺

• Aluminium chloride, Al₂Cl₆

The following mass spectrum shows that element X has 2 isotopes.

When X is reacted with oxygen-16, an oxide X₂O₃ is formed. What is the relative formula mass of X₂O₃?

• 60.46

• 64.40

• 69.60

• 72.82

Which of the following statements is true of dimer Al₂Cl₆?

• It is an ionic compound.

• Aluminium atom undergoes sp² hybridisation.

• It is a white solid which sublimates when heated.

• There are two coordinate covalent bonds in the molecule.

At constant temperature and volume, an ideal gas X exerts a pressure P atm while hydrogen exerts a pressure of 10.1P atm. Which of the following best explains this difference?

• The movement of hydrogen molecules is random.

• Intermolecular attractive forces exist between hydrogen molecules.

• The collision between hydrogen molecules and the walls of the container are not elastic

• The total volume of the hydrogen molecules cannot be ignored when compared with the volume of the container

1. A mixture of 8.0g of a monoatomic gas X and an unknown quantity of diatomic gas Y has a volume of V m³ at s.t.p. When 20.0g of gas X is added to the mixture, under the same conditions, the volume of the mixture is 2V m³. Calculate the quantity of gas y in the mixture.

[Relative atomic mass: X = 4, Y = 1. Assuming that gas X does not react with gas Y]

• 6g

• 5g

• 3g

• 2g