An element consists of two isotopes. one with a mass of 79.95 amu and an abundance of 29.9%. the second isotope has a mass of 81.95 amu with an abundance of 70.1%. what is the molar mass of this element?

 the molar  mass of the element  is  81.36 g/mol

calculation

step 1 : multiply  each %abundance  of the isotope  by   its mass  number

that is 79.95 x 29.9 =2391

           81.95 x 70.1  = 5745

Step 2: add them together

2390.5 + 5744.7 =8136

Step 3: divide by 100

= 8136/100 = 81.36  g/mol

for step 7 table c on the lab "newtons law of action"   the average time it took the car to travel .25 meters   was 1.92 seconds.

the average time it took the car to travel 0.50 meters was 2.61 seconds

hope this : )