<span>The option A is correct answer. The isotopes are X and Y. The isotopes are those which have same atomic number but different mass number. Since atomic number has same number of protons or electrons. Thus, isotopes have same number of protons or electrons. Therefore, X and Y are isotopes.</span>
Answer:
If the electronegativity of two atoms is basically the same, a nonpolar covalent bond will form, and if the electronegativity is slightly different, a polar covalent bond will form.
Explanation:
that's your answer very easy.
Answer:
The balanced half-reaction for the reduction of dichromate ion to chromium ion in acidic aqueous solution:

Explanation:
The reaction :

Balancing of reaction in an acidic medium:
Step 1: Balance the atoms in the reaction:

Step 2: Balance oxygen atom by adding water on the side where no oxygen or less oxygen atom is present;

Step 3: Balance the hydrogen atom by adding hydrogen ions on the side where water is absent:

Step 4: Now balance charge by adding electrons on the side where more positive charge is present

The balanced half-reaction for the reduction of dichromate ion to chromium ion in acidic aqueous solution:

C. mass is protons and neutrons. Both are in the nucleus
i think it is the cell wall.