What do you understand by valency electron and valency shell?

An atom of sodium-23 (atomic number = 11) has a positive charge of +1. give this information, how many electrons does it have? how many proteins and neutrons does this atom have

Main expenses you plan on making payments on a new car too. you want to spend 15% of your monthly net pay on the car payment, insurance, registration, and taxes combined. what is your monthly car allowance? $149.46 $298.91 $448.37 $597.83

What is the formula of the ionic compound composed of calcium cations and chloride anions