Atomic Number and Mass Number

The half-life of a radioisotope is $4$ hours. If the initial mass of the isotope was $200 \mathrm{g}$, the mass remaining after $24$ hours undecayed

Which statement out of the following is true? Isobars have

Radioactive isotope used in the treatment of cancer disease is 

Isotopes of an element contains 

Two elements P and Q have $5$ and $7$ electrons in their outermost shell respectively. The atomic number of P and Q will be

Two atoms are said to be isobars if 

An isotope of which element is used in the treatment of cancer?

Hydrogen contains three types of atoms (${}_1{}^1\mathrm{H}$ protium, ${}_1{}^2\mathrm{H}$ deuterium, ${}_1{}^3\mathrm{H}$ tritium). These atoms are

An element X (atomic number 12) reacts with another element Y (atomic number 17) to form a compound Z. Which of the following statements are true regarding this compound?

 $1.$ Molecular formula of Z is $X{Y}_2$

$2.$ It is soluble in water.

$3.$ X and Y are joined by sharing of electrons.

$4.$ It would conduct electricity in the molten state.

Codes:

When the neutral X atom is compared to the ion of another element Y, which of the following could be the same?

(i) Proton numbers

(ii) Electron numbers

(iii) Neutron numbers

(iv) Chemical properties

X and Y atoms are atoms of the same element. Which of the following is equal in X and Y?

(i) Proton numbers

(ii) Neutron numbers

(iii) Mass numbers

Since there are 24 electrons and 29 neutrons in X²⁺ ion, which of the following is an isotope of this ion?

In ⁸⁰X^2- ion, the number of neutrons is 10 times more than the number of electrons. What is the number of protons in the element X?

An atom with four protons and four neutrons will have a valency of:

Some information about X, Y, Z, and Q particles is given in the table.

Accordingly, which of the following about X, Y, Z, and Q is incorrect?

In a sample of ethyl ethanoate (CH₃COOC₂H₅), the two oxygen atoms have the same number of electrons but different number of neutrons. Which of the following is the correct reason for this?

The ion of an element carries 3 units of positive charges. The mass number of an atom is $27$ and the number of neutrons is $14.$ What is the number of electrons in the ion?

Which of the following is true for an element?

$\left(i\right)$ Mass number = number of protons + number of electrons

$\left(ii\right)$ Mass number = number of protons + number of neutrons

$\left(iii\right)$ Atomic mass = number of protons = number of neutrons

$\left(iv\right)$ Atomic number = number of protons = number of electrons

The number of electrons of the $X_{11}^{+}$ and ¹⁶Y^2-  ions are equal.The number of neutrons of X⁺ is four times more than the number of neutrons of Y^2-, What is the mass number of X⁺?

Which of the following is the same for  ${}_{29}{}^{63}C{u}^{+}$ and  ${}_{29}{}^{65}C{u}^{2+}$particles?