Foundations in Chemistry Random Retrieval

Which of these conversions are reductions?

(i) CrO₄^2- to Cr₂O₇^2-

(ii) CrO₄^2- to Cr³⁺

(iii) CrO₄^2- to CrO₃

(iv) CrO₃ to Cr₂O₃

What volume of 0.10 mol dm^-3 hydrochloric acid is needed to neutralise 20.0 cm³ of 0.05 mol dm^-3 barium hydroxide?

Which of these statements is true of a metallic crystal?

(i) It consists of atoms strongly held together by metallic bonding.

(ii) It consists of a regular array of positive ions in a sea of negative electrons.

(iii) The crystal is held together by the attraction between positive metal ions and electrons.

(iv) The crystal is negatively charged.

Zinc conducts electricity because:

(i) the metal is polycrystalline

(ii) the atoms are close-packed

(iii) the atoms are in contact with neighbouring atoms

(iv) the bonding electrons are delocalised.

Which of these statements are true for the hydrides of group 5: NH₃, PH₃, AsH₃ and SbH₃:

(i) the molecules decrease in size down the group

(ii) the boiling point of ammonia is higher than expected from the general trend in values down the group

(iii) none of the molecules is polar

(iv) only ammonia is affected by hydrogen bonding

What is/are the bond angle(s) found in iodine trifluoride?

(i) 104.5^o

(ii) 120^o

(iii) 107^o

(iv) 90^o

An element M has two electrons in its outer shell. An element X has seven electrons in its outer shell. What is the likely formula of the compound of X and Y?

How many electrons are there in an oxide ion?

How many neutrons are there in an atom of boron with mass number 9 and atomic number 4?