Question

Question 11

Which of the following is a trace element in the human body?

hydrogen

oxygen

zinc

nitrogen

Question 12

Which of the following statements regarding matter is false?

All matter is composed of elements.

All matter exists in the form of compounds.

All life is composed of matter.

All matter has mass.

Question 13

Which of the following statements best describes a compound?

A compound is exemplified by sodium.

A compound is a solution.

A compound contains two or more different elements in a fixed ratio.

A compound is a pure element.

Question 14

In the equation 2 H2 + O2 ? 2 H2O,

only H2O is a compound.

only H2 and O2 are compounds.

H2, O2, and H2O are all elements.

H2, O2, and H2O are all compounds.

Question 15

Which of the following particles are found in the nucleus of an atom?

neutrons and electrons

neutrons, electrons, and protons

protons and electrons

protons and neutrons

Question 16

Which of the following best describes the atomic number of an atom?

the number of electrons in the atom

the number of protons in the atom

the number of protons, electrons, and neutrons in the atom

the number of neutrons in the atom

Question 17

Typically, nitrogen atoms are composed of electrons, protons, and neutrons. An isotope of nitrogen could

be positively charged.

be negatively charged.

have more protons than the usual nitrogen atom.

have more neutrons than the usual nitrogen atom.

Question 18

When full, the innermost electron shell of argon contains ________ electrons, and the outermost shell contains ________ electrons.

2; 8

8; 8

4; 8

2; 2

Question 19

A(n) ________ forms when two atoms share electrons.

covalent bond

ion

ionic bond

hydrogen bond

Question 20

A hydrogen atom has one electron. How many covalent bonds can hydrogen form?

one

none

two

four

Answer 1

Hi Answer:

11. Which of the following is a trace element in the human body?

Answer: Option C. (Zinc)

Explanation: Trace elements are those elements which are found in very minute quantity inside the body. In case of human the, more than 70% of the body is made up of water (H₂O), whose major content is Hydrogen and oxygen. Second, the nitrogen is also present in large amount inside the body for example proteins, DNA etc. Hence these three elements C, H, and N are not in trace elements of the human body.

12. Which of the following statements regarding the matter is false?

Answer: Option B. (All matter exists in the form of compounds)

Explanation: Matter exists in three main states solid, liquid and gases. Whereas the compounds made up of atoms and molecules. The matter has mass and it occupies space.

13. Which of the following statements best describes a compound?

Answer: Option C. (A compound contains two or more different elements in a fixed ratio).

Explanation: A compound is a mixture of two or more different elements which are mixed together in a fixed ratio.

14. In the equation 2 H2 + O2 ? 2 H2O,

Answer: Option A. (only H2O is a compound).

Explanation: In above equation hydrogen and oxygen are elements and when they combined together in a fixed ratio they make a compound molecule i.e. water.

15. Which of the following particles are found in the nucleus of an atom?

Answer: Option D. (Protons and neutrons)

Explanation: Simply an atom is made up of proton, neutrons, and electrons. In which the protons are positively charged, neutrons have no charge (neutral) and electrons are negatively charged. In simple atomic structure proton and neutrons are present in the nucleus of an atom whereas the electrons orbit the atom.

16. Which of the following best describes the atomic number of an atom?

Answer: Option B. (the number of protons in the atom)

Explanation: Atomic number of an atom is equal to the total number of protons present in the nucleus of an atom. It is represented by the symbol of Z. The atomic number is unique identity of a chemical element.

17. Typically, nitrogen atoms are composed of electrons, protons, and neutrons. An isotope of nitrogen could

Answer: Option D. (have more neutrons than the usual nitrogen atom)

Explanation: Isotope is the different form of the same element who have an equal number of protons but a different number of neutrons in their nuclei. Due to the presence of different neutrons, they have different atomic mass but their chemical properties are same.

18. When full, the innermost electron shell of argon contains 2 electrons, and the outermost shell contains 8 electrons.

Explanation: Argon is the chemical element having atomic number 18 which is an inert gaseous element because its inner and outer most shells are totally filled with electrons so didn’t make sharing of their electron with other elements that's why it’s known as an inert element.

19. Covalent bond forms when two atoms share electrons.

Explanation: The covalent bond is formed by sharing of electrons between atoms. It is most stable bonding because by sharing the electron the atom achieved its stable electronic configuration.

20. A hydrogen atom has one electron. How many covalent bonds can hydrogen from?

Answer: Option A. (Single)

Explanation: As hydrogen has atomic number 1. It has only one electron and it can able to make only one covalent bond with other atoms. Example H₂, OH