Chemistry

An aqueous solution of CaCl is

• Acidic

• Alkaline

• Buffer

• Neutral

• Acidic

Which of the following compounds would dissolve in water to give a solution whose pH is less than 7

• Al(NO3)3

• KNO3

• N2O

• NH3

• N2O

The mass spectrometer can be used to measure

• Atom

• Electron

• Proton

• Neutron

• Atom

An atom has a mass number of 45 and an atomic number of 21 what is it's neutron number

• 21

• 24

• 45

• 66

• 24

A radioactive element with mass number 234 and atomic number 88 decay by alpha emission to give an atom R what is the atomic and mass number of atom R

• 86 and 230

• 87 and 234

• 88 and 233

• 90 and 238

• 86 and 230

Which of the following statements is not true of halogens

• They exists in different physical states

• They exist as diatomic molecules

• Their ionic radii decrease down the group

• Their melting and boiling point decrease down the group

• Their ionic radii decreases down the group

Elements in the same group in the periodic table have

• The same number of valence electrons

• The same number of electrons shells

• Different chemical behaviour

• The same atomic size

• The same number of valence electrons

Water molecules are held together by

• Covalent bonds

• Hydrogen bonds

• Ionic bonds

• Van der Waals force

• Hydrogen bonds

If 5cm3 of 0.02 mol/dm3 Na2CO3 was diluted with distilled water to obtain 250cm3 solution what is the concentration of the resulting. Solution

• 0.004mol/dm3

• 0.002mol/dm3

• 0.2mol/dm3

• 0.4mol/dm3

• 0.004mol/dm3

The high solubility of ethanol is due to its

• Low boiling point

• Low freezing point

• Covalent nature

• Hydrogen bonding

• Hydrogen bonding