Practice questions

• Answer =

  47.8 = 46 * 2x + 47 * 2x + 48 *(100-5X) * 49x

  = 8 %

  Question

  
• Answer

  52.2 = (86.1 * 52) + 50x + 53 * (13.9 -x)/100

  1.3% = Cr50

  13.9-1.3 =

  12.6% = Cr 53


  Question

  
• Answer

  Stage 1: General Trend (Li → Ne)

  1a. 1st IE increases

  1b. More protons/increased nuclear charge

  1c. Electrons in same energy level / shell 1d. No extra/similar shielding

  Stage 2: Deviation Be → B

  2a. B lower than Be

  2b. Outer electron in 2p

  2c. higher in energy than (2)s so weaker attraction

  Stage 3: Deviation N → O

  3a. O lower than N

  3b. 2 electrons in 2p need to pair

  3c. pairing causes repulsion (do not award if it is clear reference to repulsion is in s orbital)


  Question