An atom with 3 protons and 4 neutrons will have a valency ofa) 3 b) 7 c) 1 d) 4

To determine the valency of an atom with 3 protons and 4 neutrons, we need to look at the number of valence electrons.

The number of protons in an atom determines its atomic number, which also corresponds to the number of electrons in a neutral atom. In this case, the atom has 3 protons, so it will have 3 electrons.

To find the valency, we need to consider the number of electrons needed to complete the outermost energy level. For most elements, the outermost energy level can hold a maximum of 8 electrons. However, in this case, the atom only has 3 electrons.

Since the atom needs 5 more electrons to complete its outermost energy level, the valency will be 5.

Therefore, the correct answer is d) 5.