What is the shape of a methane molecule?
- A.Linear
- B.Trigonal planar
- C.Tetrahedral
- D.Pyramidal
Correct answer
Explanation
The correct answer is C, tetrahedral. In methane the carbon atom is joined to four hydrogen atoms by four single bonds and has no lone pair, so the four bonding pairs push one another as far apart as possible and point to the corners of a regular tetrahedron, with bond angles of about 109.5 degrees. Option A is wrong because a linear shape, with a bond angle of 180 degrees, belongs to molecules such as carbon dioxide and acetylene. Option B is wrong because a trigonal planar shape, with angles of 120 degrees, belongs to molecules such as boron trifluoride, which has only three bonding pairs. Option D is wrong because a pyramidal shape belongs to ammonia, where one lone pair on nitrogen pushes the three bonds down to an angle of about 107 degrees. Water, with two lone pairs, is bent at about 104.5 degrees; learn these four shapes together.
Read the full article: Chemical Bonding and Reactions: Types, Rules and Facts
Practice Questions
View allWhich of the following is NOT a double displacement reaction?
- A.BaCl2 + H2SO4 → BaSO4 + 2HCl
- B.2H2 + O2 → 2H2O
- C.CuSO4 + H2S → CuS + H2SO4
- D.NaOH + HCl → NaCl + H2O
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In a double displacement reaction two compounds exchange their ions, so both reactants must be compounds. Here hydrogen and oxygen are elements combining to form a single product, water, which makes it a combination reaction and also a combustion and redox reaction, but certainly not a double displacement.
Read the full explanation →Which among the following compounds has a double bond?
- A.Ethane
- B.Methane
- C.Acetylene
- D.Ethylene
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Ethylene, also called ethene, has the formula C2H4, and its two carbon atoms share two pairs of electrons, which is a carbon-carbon double bond made of one sigma and one pi bond; it is the simplest alkene.
Read the full explanation →The number of sigma and pi bonds in benzene, respectively, is:
- A.12 and 3
- B.3 and 3
- C.6 and 3
- D.9 and 3
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Benzene has the formula C6H6 and a ring of six carbon atoms, each carrying one hydrogen. Count the sigma bonds first: six carbon-carbon bonds around the ring and six carbon-hydrogen bonds give twelve sigma bonds.
Read the full explanation →Which of the following is an amphoteric oxide?
- A.Aluminium oxide
- B.Iron (II) oxide
- C.Magnesium oxide
- D.Carbon dioxide
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An amphoteric oxide reacts with both acids and bases to give a salt and water. Aluminium oxide dissolves in hydrochloric acid to give aluminium chloride and in sodium hydroxide to give sodium aluminate, so it behaves as a base in one case and as an acid in the other.
Read the full explanation →Which of the following is used as a catalyst in the hydrogenation of vegetable oil?
- A.Pb
- B.Ni
- C.H2
- D.He
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Vegetable oils contain unsaturated fatty acids with carbon-carbon double bonds, and when hydrogen is passed through the oil at about 60 degrees Celsius in the presence of finely divided nickel, the double bonds add hydrogen and become saturated, turning the liquid oil into semi-solid vanaspati.
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