Answer:
See the answer below
Explanation:
<em>The duration of flushing the eyes at the eyewash station in case of accidental contact with chemicals depends of the nature of the chemical.</em>
If the chemical is known to be a <u>non-irritant or mild-irritant</u> one, a <u>5-minute </u>washing time is recommended as the first aid. before seeking the help of a physician,
For <u>moderate to severe irritant</u> chemicals, an immediate <u>15-20 minutes</u> washing period is recommended before seeking further medical help.
For <u>corrosive and strong alkalis</u> chemicals, <u>30 and 60 minutes</u> washing are recommended respectively before seeking the attention of a physician.
However, if the nature of the chemical is unknown,<u> a minimum of 20-minutes washing is generally recommended</u> as first aid before seeking immediate medical help.
Complete Question
The complete question is shown on the first uploaded image
Answer:
The concentration of
that should used originally is 
Explanation:
From the question we are told that
The necessary elementary step is

The time taken for sixth of 0.5 M of reactant to react 
The time available is 
The desired concentration to remain
Let Z be the reactant , Y be the first product and X the second product
Generally the elementary rate law is mathematically as

Where k is the rate constant ,
is the concentration of Z
From the elementary rate law we see that the reaction is second order (This because the concentration of the reactant is raised to power 2 )
For second order reaction

Where
is the initial concentration of Z which a value of 
From the question we are told that it take 9 hours for the concentration of the reactant to become


So


=> 
For 





I will mark you brainlist please help
1) A ball is thrown with the speed of 10 m/s from the 1st stair. The height of each stair is 10cm and the width is 15 cm. on which stair the ball will fall