Element X Is a Solid at room temperature
Is a metalloid and semiconductor of heat and
electricity
Reacts with Oxygen to form XO2,
compounds and with chlorine to form XCI4,
compounds
Has an average atomic mass that is 2.34
times greater than the standard for atomic
mass(Carbon-12)

Because a model would make the investigation easier to understand

The independent variable is the type of music.the dependent variable is the pulse rate.the intervening variable is the age of the subject.if the mother does not like rock, her pulse is likely to not increase.the same might be true for the sister.the friend may like rap and gets excited.to establish cause/effect relationship, all of the subjects must be consistent.hope i .

A.(nh4)(2co3)is the correct answer