Answer:
v = 1.5 m/s
Explanation:
Given that,
Distance covered by a person, d = 105 m
Time taken, t = 70 s
We need to find the average speed of the person. We know that the average speed is given by :

So, the average speed of the person is equal to 1.5 m/s.
 
        
             
        
        
        
Option C: elements produce spectra with only few distinct lines.
The spectra are not continuos and are different for every element. This permits to identify elements.
        
             
        
        
        
C is the answer hope this helps
        
             
        
        
        
Answer:
A process during which chemical bonds between atoms are broken and new ones are formed, producing one or more substances.
Moles are the amount of substance that contains as many particles.
Explanation:
A chemical reaction is when a chemical change occurs for example when a nail comes into contact with air and is then exposed to air it begins to rust. It forms a red-brown substance which changes the chemical composition of the original compound. 
Examples of chemical reactions: 
Combustion
Oxidation (rusting)
Cooking an egg
Photosynthesis
Digestion
Fireworks
Paper Burnin
The mole is the amount of substance that contains as many particles (molecules, ions or atoms) as there are in 12g of carbon. 
1 mol is the amount of substance that contains the same number of particles as there are atoms in 12.0 g of carbon-12 and that number is referred to as Avogardo's constant (6.022 x  ).
).