Refractive Index is a ratio of two similar physical quantity which is dimension less 
refractive index = sin I / sin r 
therefore it doesn't have a unit.
        
                    
             
        
        
        
Answer:
- Water gained: 10
- Iron lost: -10
Explanation:
Given: Hot iron bar is placed 100ml 22C water, the water temperature rises to 32C
To find: How much heat the water gain, how much heat did the iron bar lost
Formula:Q = change T x C x M
Solve: 
<u>How much heat water gained</u>
Initial heat = 22, then rose to 32. To find how much heat the water gained, simply subtract the current heat by the initial heat.
                                               32 - 22 = 10
The water gained 10 amounts of heat.
<u>How much heat Iron lost</u>
Current heat = 32, then dropped to 22. To find how much heat the Iron lost, simply subtract the initial heat by the current heat.
                                                    22 - 32 = -10
The Iron lost -10 amounts of water.      
 
        
             
        
        
        
Answer:
A
Explanation: A is a example of Air resistance force, which is a contact force.
 
        
                    
             
        
        
        

As per as my knowledge 
The speed of a wave in a medium is affected by <u>d</u><u>e</u><u>n</u><u>s</u><u>i</u><u>t</u><u>y</u>,<u> </u><u>w</u><u>a</u><u>v</u><u>e</u><u>l</u><u>e</u><u>n</u><u>g</u><u>t</u><u>h</u> and <u>t</u><u>e</u><u>m</u><u>p</u><u>e</u><u>r</u><u>a</u><u>t</u><u>u</u><u>r</u><u>e</u><u> </u>:)
(Good luck on your test and mark me brainliest if this helps)
 
        
             
        
        
        
Internal energy of the system changes by ΔE = 178 J.
Heat given to the system = Q = +658 J.
According to the first law of thermodynamics, 
ΔE = Q + W
178 = 658 + W 
∴ W = 178-658 = -480 J
Minus sign indicates that work is done by the system.