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select the choice that best completes the following sentence.

simple machines
a.
are tools that make work easier.
b.
reduce the amount of energy needed to do work.
c.
are made up of multiple moving parts.
d.
cannot be combined to make compound machines.

Which of the following observations indicates that there is a small, dense, positively charged part in the center of an atom? some uncharged particles are scattered by a gold foil. all uncharged particles are attracted towards a gold foil. all positively charged particles pass straight through a gold foil. some positively charged particles bounce back from a gold foil.

Name the element in group 17, period 2. (periodic table)

Imagine that twenty i. u.’s of enzyme z were catalyzing the above reaction for one minute, under vmaxconditions, in a 3.00 ml assay volume. the assay is buffered with 20 mm phosphate buffer, ph 7.60. what will the ph be at the end of that one minute?