Chemistry Year 12 Random Retrieval

One mole of an alkane needs 8 moles of oxygen for complete combustion. What is the molecular formula of the alkane?

Which of these true statements help to explain why the values of the first ionisation enthalpies (energies) of the group 1 metals fall down the group from lithium to caesium?

(i) Down the group, the outer electron gets further from the nucleus

(ii) The charge on the nucleus increases down the group

(iii) Greater shielding means that the attraction between the nucleus and the outer electron reduces down the group

(iv) In all the atoms the outer electron is an s-electron

Which of these statements about atomic and ionic radii are true?

(i) Atomic radii increase down group 2

(ii) Ionic radii increase down group 7

(iii) Atomic radii decrease across period 3

(iv) In period 3 the ionic radii are smaller than the atomic radii

Which of the following increase from left to right across the series F₂ - Cl₂ - Br₂?

(i) covalent radius of the atoms

(ii) electronegativitiy

(iii) boiling point

(iv) strength as an oxidising agent

For which of the following equations is the value for standard enthalpy change equal to the standard enthalpy of formation of sodium chloride?

How many electrons are there in an oxide ion?

Which of these molecules are overall non-polar?

(i) H₂O

(ii) CO₂

(iii) SO₂

(iv) CCl₄

Which of these sets of properties is that of a group 1 metal?

Which of these true statements can help to explain why magnesium has a higher melting point than sodium:

(i) magnesium atoms/ions are smaller than sodium atoms/ions

(ii) the metallic bonds are stronger in magnesium than in sodium

(iii) a magnesium atoms contributes two bonding electrons not one

(iv) the first ionisation energy is higher for magnesium than for sodium.