I took in chemical lab experiment called(molecular mass of volatil liquid ) in this experiment they said we should make a hole in the aluminum foils by needle ... my question is why we should make a holl in the aluminum ?? #chemical​

The tilt of the earth's axis of rotation is responsible for the a) ocean's tides. b) size of the moon. c) brightness of stars. d) earth’s seasons.

Choose an equation that represents an enzyme-catalyzed reaction. (a) enzyme + substrate → enzyme-substrate complex (b) enzyme + substrate ←−→ enzyme + products (c) enzyme + substrate ←−→ enzyme-substrate complex → enzyme + products (d) enzyme + substrate ←−→ enzyme-substrate complex → enzyme-substrate complex + products

Which statement about hf is true? it is zero for any compound in its standard state. it is positive when the bonds of the product store more energy than those of the reactants. it is negative when a compound forms from elements in their standard states. it is zero for any element that is in the liquid state.