Answer:
The dolphins average speed is 3.51 
Explanation:
First of all, the following rules of three should be applied:
- If 1 mile is equal to 1609 meters, 20 miles are equal to how many meters?

distance=32,180 meters
- If 1 minute is equal to 60 seconds, 153 minutes is equal to how many seconds?

time= 9,180 seconds
Speed is a physical quantity that expresses the relationship between the space traveled by an object and the time used for it. That is, speed implies the change of position of an object in space within a certain amount of time and is calculated as:

So in this case the velocity is calculated as:

Solving, you get:
Speed= 3.51 
<u><em>The dolphins average speed is 3.51 </em></u>
<u><em></em></u>
Answer:
Zn(s) + 2H₂O (l) → Zn(OH)2(aq) + H2(g)
Sn(s) + O2(g) →SnO2(s)
Cd(s) + Pb(NO3)2 (aq) →Cd(NO3)2 (aq) + Pb(s)
Cu (s) + HCl(aq) → can not occur
Explanation:
Metals reacts with liquid water to yield the corresponding metallic hydroxide and hydrogen gas as shown above; Zn(s) + 2H₂O (l) → Zn(OH)2(aq) + H2(g)
Tin reacts with oxygen to yield tin (IV) oxide. This is an oxidation reaction as shown; Sn(s) + O2(g) →SnO2(s)
The reaction between Cd and Pb(NO3)2 is a single replacement reaction. It is possible because Cd is above Pb in the electrochemical series. Hence the reaction occurs thus; Cd(s) + Pb(NO3)2 (aq) →Cd(NO3)2 (aq) + Pb(s)
Copper does not displace hydrogen from dilute acids (such as HCl) since copper is lower than hydrogen in the electrochemical series hence the reaction does not occur.
If magnets are heated to the Curie point, they lose their ability to be magnetic. ... Cooling causes the molecules in the magnet to have less kinetic energy. This means that there is less vibration in the magnet's molecules, allowing the magnetic field they create to be more consistently concentrated in a given direction.
Given :
Number of molecules of
.
To Find :
How many moles are in given number of molecules.
Solution :
We know, in 1 moles of any element/compound contains
at atoms/molecules.
So, number of moles in
molecules are :

Therefore, number of moles are 8.97 .