What semimetal can form four single covalent bonds.

The right answer is Sillicon.

Silicon (Si) is the chemical element of atomic number 14. It is the most abundant element in the earth's crust after oxygen, or 25.7% of its mass, but it is comparatively only present in relatively small quantities in the material constituting the living.

It is a semi-metal, ie it does not meet all the criteria to be defined as being a metal.

It has four free electrons in the last orbit, so it is able to form four covalent bonds. (the carbon can form 4 covalent bonds but it is not a semi-metal)

when [oh-] is 10-5  m, and [h3o+] is 10-9  m, the poh is 5 and ph is 9. again in both cases the sum of ph and poh is 14. however, the hydrogen ion concentration is not always going to be equal to exactly 1 x 10 raised to a negative number. for example, we skipped over the value of 2.0 x 10-7.

conduction is the transfer of thermal energy (heat in transfer) due to collisions between the molecules in the object. collisions between adjacent atoms and molecules transfer kinetic energy from the warmer to the cooler object. the objects must be in physical contact.