Vhich statements explain current theories about dark energy and dark matter?

What semimetal can form four single covalent bonds.

In a water molecule, hydrogen and oxygen are held together by a(an) bond. a) double covalent b) ionic c) nonpolar covalent d) hydrogen e) polar covalent

Apiece of metal with a length of 1.42 cm was measured using four different instruments. which of the following measurements is the most accurate?