Answer:
period 3 and group 3
Explanation:
I'm saying group 3 because that is how I learnt it at school, but if you count it then it's in group 13.
A positive acceleration indicates that the object sped up. This means that if you compare the first speed to the second, the second speed should be higher.
A negative acceleration indicates that the object has slowed down. This means that if you compare the first speed to the second, the second speed should be lower.
If an acceleration is 0, it means that it neither slowed down nor sped up.
Now let us analyze your problem by listing down the speed and the time:
At noon: 4 mi/hr
12:30 : 6 mi/hr
2:30 : 2 mi/hr
From noon to 12:30, you will notice that there is an increase in speed. This means that Tommy had a positive acceleration. (Rules out D.)
From 12:30 to 2:30, there is a decrease in speed. This would indicate that Tommy had a negative acceleration. (Rules out C.)
No speed was the same, so acceleration was never 0. (Rules out A.)
From the assumptions above, we can now deduce that the answer is B.
Answer: Thus 0.724 mol of 
are needed to obtain 18.6 g of 
Explanation:
To calculate the moles :
According to stoichiometry :
2 moles of are produced by = 1 mole of
Thus 1.09 moles of will be produced by =
of
But as yield of reaction is 75.6 %, the amount of needed is =
Thus 0.724 mol of are needed to obtain 18.6 g of
Answer:
B: circulatory system
Explanation:
The circulatory system is made up of blood vessels that carry blood away from and towards the heart. Arteries carry blood away from the heart and veins carry blood back to the heart. The circulatory system carries oxygen, nutrients, and hormones to cells, and removes waste products, like carbon dioxide.
