Pacemakers maintain the heartbeat in people who suffer from certain defects. the function of an artificial pace is to send electrical impulses that will contract the heart muscles and regulate the pumping of the heart. which condition could be corrected by a pacemaker?

25) a student takes four samples of a white crystalline solid and places each in a well plate. on top of each sample, she carefully places 20 drops of clear mystery liquids a, b, c and d. her results for each well are: liquid a: the solid dissolves quickly. liquid b: the solid appears unchanged. liquid c: a brownish colored liquid is produced. liquid d: fizzing occurs and the well becomes warmer. in which well does a physical change occur?

Fossils can only be formed when? if mud, silt or tar is in the area to preserve the fossil ierosion does not occur and allows the fossil to form oxygen and microorganisms cannot decay the bones the area is dry and does not contain mud or silt

Natural selection changes allele frequencies because some survive and reproduce more successfully than others.