1.
What is the smallest particle of an element that retains its properties?
Correct Answer
C. Atom
Explanation
An atom is the smallest particle of an element that retains its properties. It consists of a nucleus containing protons (positively charged) and neutrons (neutral), surrounded by electrons (negatively charged) in orbitals. Atoms combine to form molecules, but an individual atom retains its characteristic properties such as atomic number and chemical behavior.
2.
How many electrons can the first shell of an atom hold?
Correct Answer
A. 2
Explanation
The first shell of an atom, also known as the K-shell, can hold a maximum of 2 electrons. This shell fills with electrons before subsequent shells begin to fill. The electron configuration determines the chemical properties and reactivity of an element, with electrons occupying specific energy levels or shells around the nucleus.
3.
Which subatomic particle has a positive charge?
Correct Answer
C. Proton
Explanation
Protons are subatomic particles with a positive charge. They are located in the nucleus of an atom alongside neutrons, contributing to the atom's mass and defining its atomic number. Protons are crucial in determining the identity of an element, as each element has a unique number of protons in its nucleus.
4.
What is the atomic number of an element based on?
Correct Answer
C. Number of protons
Explanation
The atomic number of an element is based on the number of protons in its nucleus. This number defines the element's identity and position in the periodic table. Elements with the same atomic number share similar chemical properties, reflecting their identical number of protons and electron configurations.
5.
Which group of elements in the periodic table is known as the "noble gases"?
Correct Answer
D. Group 18
Explanation
Group 18 elements in the periodic table are known as noble gases. They are characterized by their stable electron configurations with a full outer shell of electrons, making them inert and less reactive compared to other elements. Noble gases include helium, neon, argon, krypton, xenon, and radon.
6.
What is the chemical symbol for iron?
Correct Answer
B. Fe
Explanation
The chemical symbol for iron is Fe, derived from its Latin name "ferrum." Chemical symbols are shorthand representations of elements used in chemical formulas and equations. Each element has a unique symbol, typically derived from its English or Latin name, allowing for concise and universal communication in chemistry.
7.
Which element is essential for human bones and teeth?
Correct Answer
B. Calcium
Explanation
Calcium is essential for human bones and teeth. It plays a vital role in bone structure and function, aiding in muscle contraction, nerve transmission, and blood clotting. Calcium is obtained through diet and supplements, ensuring proper skeletal development and maintaining bone density throughout life.
8.
What is the most abundant element in the Earth's crust?
Correct Answer
A. Oxygen
Explanation
Oxygen is the most abundant element in the Earth's crust, comprising approximately 46.6% by mass. It forms compounds with most other elements, contributing to the composition of minerals and rocks. Oxygen's abundance and chemical reactivity make it fundamental to Earth's geological processes and the sustenance of life.
9.
Which metal exists as a liquid at room temperature?
Correct Answer
C. Mercury
Explanation
Mercury (Hg) is the only metal that exists as a liquid at room temperature. It has a melting point of approximately -38.83°C (-37.89°F), which is far below typical room temperature, allowing it to remain in a liquid state under normal conditions. Mercury is a heavy, silvery metal that is often used in thermometers, barometers, and other scientific instruments because it expands and contracts uniformly with changes in temperature. Its high density and cohesive properties make it useful in various industrial applications, such as in the production of fluorescent lamps and in the mining of gold and silver, where it is used to form amalgams.
10.
What is the atomic mass of an element determined by?
Correct Answer
D. Protons and neutrons
Explanation
The atomic mass of an element is determined by the combined mass of its protons and neutrons in the nucleus. It is expressed in atomic mass units (amu) and represents the average mass of isotopes of an element found in nature. Atomic mass influences an element's chemical behavior and physical properties, providing valuable information for scientific research and practical applications.