The radium isotope 223Ra, an alpha emitter, has a half-life of 11.43 days. You happen to have a 1.0 g cube of 223Ra, so you decide to use it to boil water for tea. You fill a well-insulated container with 460 mL of water at 16∘ and drop in the cube of radium.

Not sure but i think it's b.

Can you give more detail  

Stars are born within the clouds of dust and scattered throughout most galaxies. a familiar example of such as a dust cloud is the orion nebula. turbulence deep within these clouds gives rise to knots with sufficient mass that the gas and dust can begin to collapse under its own gravitational attraction. as the cloud collapses, the material at the center begins to heat up. known as a protostar, it is this hot core at the heart of the collapsing cloud that will one day become a star. three-dimensional computer models of star formation predict that the spinning clouds of collapsing gas and dust may break up into two or three blobs; this would explain why the majority the stars in the milky way are paired or in groups of multiple stars.therefor, i would say the answer is: dust and gases contract.i hope this ! < 3

D. engine coolant temperature