Which principal energy level can hold a maximum of 18 electrons

An atom of lithium-7 has an equal number of(1) electrons and neutrons(2) electrons and protons(3) positrons and neutrons(4) positrons and protons

Total the mass on the syringe. record it in the correct row of the data table. kg done click and drag weights to change the pressure. click the syringe to zoom in and see the volume. intro

Why must humans find substitutes for many minerals found on earth? (a) form at an extremely slow rate (b) controlled by other countries (c) too deep in the earth to collect