Answer:
Which of the following happens during a lunar eclipse?
Select one:
a. Earth casts a shadow on the moon.
<u>b. The moon casts a shadow on Earth.
</u>
c. Earth stops revolving in its orbit.
d. Earth starts revolving around the moon.
Explanation:
Answer: 7
Explanation:
Before a number but after a decimal. The zeros at the end would usually mean that it doesn't count but since the numbers are before the zeros and after a decimal it's 7 sig figs
<span> First you need to know how many isotopes there are of silicon, and its average atomic units (look at periodic table). Then make up a system of equations to solve for it. Theres 3 stable silicon isotopes (28, 29, 30) so you will need to have 3 equations. You must be given the percent abundance of at least one of the isotopes to solve because here I can only see 2 equations (numbered down below) set x = percent abundance of si-28 y = percent abundance of si-29 z = percent abundance of si-30 since all of silicon atoms account for 100% of all silicon: x + y + z = 100% = 1 therefore: 1) x = 1 - y - z You also have 2) 28x + 29y + 30z = average atomic mass you can substitute x so that equation becomes: 28 (1 - y - z) + 29y + 30z = average atomic mass See how you have 2 variables here? You cant go on until you know the value of one isotope already or you have given a clue which you can derive the third equation</span>
Answer:
286 kPa
Explanation:
Boyles law states that volume of gas is inversely proportional to pressure o gas for a fixed amount of gas at constant temperature
P1V1 = P2V2
where P1 is pressure and V1 is volume at first instance
P2 is pressure and V2 is volume at the second instance
substituting the values in the equation
229 kPa x 4.0 L = P2 x 3.2 L
P2 = 286.25 kPa
the new pressure is 286 kPa
