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- The symbols of two elements are 199Q and 4020R. If P and Q combine to form a compound, what is the relative formula mass of this compound?
- Which substance is used as flavourings?
- Sodium nitrite
- Azo compounds
- Ascorbic acid
- Monosodium glutamate*
- Which of the following ions reduce the effectiveness of soaps in hard water?
- Calcium ions and sodium ions
- Aluminium ions and iron(II) ions
- Calcium ions and magnesium ions
- Magnesium ions and potassium ions
- Half equation below represents a reaction.
2I– → I2 + 2e
What is meant by oxidation reaction based on the equation ?
- Electrons are received by iodine
- Electrons are received by iodide ion
- Electrons are released by iodine
- Electrons are released by iodide ions
- The following equation represents the oxidation of magnesium atom.
Mg → Mg2+ + 2e
What is meant by oxidation based on the equation?
- Electrons are received by magnesium ion
- Electrons are donated by magnesium ion
- Electrons are received by magnesium atom
- Electrons are donated by magnesium atom
- Diagram below shows a type of chemical cell. Which of the following statements is correct?
- This is a non-rechargeable cell
- The lead plate coated with lead(IV) oxide is the positive terminal of the cell
- Oxidation reaction occurs at the positve terminal
- The electrolit used is nitric acid
- Metal X is soft and shiny. It reacts with cold water to produce an alkaline solution.
What is metal X?
- 1 mol dm-3 solution X is electrolysed using carbon electrodes. A greenish-yellow gas with a pungent and choking smell is released at the anode. Which of the following may be solution X?
- 0.0001 mol dm-3 potassium sulphate
- 0.0001 mol dm-3 hydrochloric acid
- 2 mol dm-3 potassium sulphate
- 2 mol dm-3 hydrochloric acid
- Which statements are true about elements when going across Period 3?
- The atomic size of elements increase.
- The electronegativity of atoms of the elements increase.
- The properties of the oxide of the elements change from basic oxide to ampotheric oxide and acidic oxide.
- The nuclei force of attraction of atoms towards electron to achieve stable electron arrangement becomes weaker.
- Which of the following pairs show the correct uses of the isotopes?
- Cobalt-60: To destroy bacteria in food
- Carbon-14: To estimate the age of artifacts
- Iodine-131: To detect the location of tumour
- Sodium-24: To detect leaks in underground petroleum piping