I. CHOOSE THE CORRECT ANSWER:
1. There are two electrons in the outermost orbit of magnesium
atom,
hence the valency of magnesium is _________
(a)3 (b) 2 (c) 4 (d) 1
2. Which of the following gas is used to fill in balloon?
(a)Hydrogen (b) Helium (c) Chlorine (d) Nitrogen
3. The charge of neutron is _________
(a)Positive (b) Negative (c) Neutral (d) None of the above
4. The mass and atomic number of Sodium is ________
(a)11,23 (b) 14,24 (c) 23,11 (d) 12.26
II. ANSWER IN ONE WORD:
1. Give example for Isobars.
2. Name the element present in banana.
3. What is valency of carbon?
4. Write the mass number of Lithium.
III. ANSWER THE FOLLOWING:
1. Distinguish isotopes from isobar.
2. Define Mass number
Answers
Answer:
2
nitrogen
neutral
12.26
please mark as best answer and thank me please I
CHOOSE THE CORRECT ANSWER:
1) 3
2) helium
3)neutal
4)23,11
Answers in one word:
1. An example of a series of isobars would be 40S, 40Cl, 40Ar, 40K, and 40Ca.
2. potassium
3. Valency of an element is a measure of its combining power with other atoms when it forms chemical compounds or molecules.
4. 6.941 atomic mass units
Answers the following:
ANSWERS---------------)
1) * ISOBARS
•Chemicals elements which have the same mass.
•The atomic masses are equal.
•Often the physical properties are similar.
•Atomic numbers are different.
•Chemical elements are different.
* ISOTOPES
•Different atomic structure of the same element.
•The atomic masses are different.
•Usually, physical properties are different.
•Atomic numbers are the same.
•same chemical elements but in different forms.
2) The mass number (symbol A, from the German word Atomgewicht [atomic weight]),[1] also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. It is approximately equal to the atomic (also known as isotopic) mass of the atom expressed in atomic mass units. Since protons and neutrons are both baryons, the mass number A is identical with the baryon number B as of the nucleus as of the whole atom or ion. The mass number is different for each different isotope of a chemical element. Hence, the difference between the mass number and the atomic number Z gives the number of neutrons (N) in a given nucleus: N = A − Z.[2]
The mass number is written either after the element name or as a superscript to the left of an element's symbol. For example, the most common isotope of carbon is carbon-12, or 12
C
, which has 6 protons and 6 neutrons. The full isotope symbol would also have the atomic number (Z) as a subscript to the left of the element symbol directly below the mass number: 12
6C
.[3]