9. What lab equipment is used to spread heat when heating to prevent glassware from cracking breaking?

It's called ”wire gauze”, a metal mesh used with a ring clamp to support glassware over a Bunsen burner. Spreads flame out for more even heating rates.

North atlantic current or north atlantic drift is the answer

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 .