If the temperature of 24.6 g of calcium is decreased from 48.8 °C to 15.0 °C. How much heat has been released by calcium? Is the reaction exothermic or endothermic?
( the specific heat of calcium at 25 ^ C is 0.647)
A. q= 538 joules, the reaction is endothermic
B. q= 538 joules, the reaction is exothermic
C. q= -538 the reaction is endothermic
D. q= -538 joules, the reaction is exothermic

Rocks, as they are compressed, begin forming mountains above the earth's surface when two continental plates converge. the continental crust increases in depth as the mountains grow above. the himalayan mountains formed at a convergent plate boundary in this manner. the rocks are smashed together causing them to due to the intense heat and pressure from the colliding plates and eventually forming rock. a) melt; igneous b) layer; sedimentary c) recrystallize; metamorphic d) melt into the earth's interior; metamorphic

The content of manganese (mn) in steel was determined spectrophotometrically and with the use of the standard addition method. an unknown sample of mn from a digested steel sample gave an absorbance of 0.185 when analyzed spectrophotometrically. when 5.00 ml of solution containing 95.5 ppm mn was added to 50.0 ml of the unknown steel solution (digested sample), the absorbance was 0.248. calculate the concentration, in parts-per-million (ppm), of mn in the digested steel sample solution.

Light waves can move through , but they travel fastest when they move through a(n) .