Basic Chemistry Quiz
1 / 5
The atomic number of an atom is:
The correct answer is B. Although the number of electrons and protons is identical in a neutral atom, a change in the number of electrons does not change the identity of the atom, while a change in the number of protons does. The sum of the protons and neutrons is the mass number.
2 / 5
Under normal conditions, how do alkali metals, such as sodium, form ions?
The correct answer is A. The alkali metals, located in the first column of the periodic table, have one valence electron. They normally form ions by losing that electron, leaving the highest energy level empty.
3 / 5
How do chemical changes differ from physical changes?
A is the correct answer. Chemical changes involve changes in chemical bonds to form new substances. Only chemical changes can release or absorb energy. According to the law of conservation of mass, matter is neither created nor destroyed during a chemical or physical change. Only nuclear reactions affect the nucleus, not chemical or physical changes.
4 / 5
The activation energy of a reaction:
The correct answer is A. The activation energy of a chemical reaction is lowered by catalysts. The other choices are not correct because the activation energy can be either lower or higher than the energy of the reactants (kinetic or potential) depending on their temperature.
5 / 5
How many ions are created by the dissolution of 1 mole of calcium chloride, CaCl2?
The correct answer is C. Each mole of calcium chloride dissolves to form 3 moles of ions: 1 mole of Ca2+ and two moles of Cl−. The equation to solve is:
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