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Reil [10]
3 years ago
12

4. What is the function of the iris? A It converts light into electrical signals that are sent to the brain through the optic ne

rve. B It contracts and expands to control the amount of light that enters the eye. C Its curved surface helps to focus light entering the eye. D It focuses the light onto the light-sensor cells at the back of the eye.
Chemistry
2 answers:
Vanyuwa [196]3 years ago
5 0

Answer: B

Explanation: The iris of the eye will contract and expand to control the size of the pupil. The pupil allows light to enter through the eye, therefore the iris will contract and expand in order to control the amount of light that enters the eye.

Evgesh-ka [11]3 years ago
3 0

Answer: B It contracts and expands to control the amount of light that enters the eye.

Explanation:

The iris is the circular and thin structure of the eye. It is responsible for regulating the size of the pupil. This when expands and contracts controls the amount of light entering the eye's retina.

When the bright light enters the eye the iris closed the pupil so that less light enters the eye. But when the light is low, the iris open the pupil to allow more light to enter the eye and focuses the light rays onto the retina.

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Determine the mass of 2.5 cups of water if the density of water is 1.00 g/cm3 and 1 cup = 240 mL\
Schach [20]
<span>600 grams. 2,5 times 240 yields a result of 600 ml in 2.5 cups. A milliliter is equal to a cubic centimeter of liquid. As water has a mass of 1 gram per cubic centimeter, 600 milliliters of water has a mass of 600 grams.</span>
4 0
3 years ago
9 moles of Ammonia (NH3) are added to 50 L of H2O at a temperature of 29°C. The vapor pressure of water alone is 29.96 mmHg at 2
Westkost [7]

Answer:  The vapor pressure of the solution at 29^0C is 29.86 mm Hg

Explanation:

As the relative lowering of vapor pressure is directly proportional to the amount of dissolved solute.

The formula for relative lowering of vapor pressure will be,

\frac{p^o-p_s}{p^o}=i\times x_2

where,

\frac{p^o-p_s}{p^o}= relative lowering in vapor pressure

i = Van'T Hoff factor = 1 (for non electrolytes)

x_2 = mole fraction of solute  

=\frac{\text {moles of solute}}{\text {total moles}}

Given : 9 moles of NH_3 are dissolved in 50 L or 50000 ml of water

mass of water = density\times volume = 1g/ml\times 50000ml=50000g  

moles of solvent (water) = \frac{\text{Given mass}}{\text {Molar mass}}=\frac{50000g}{18g/mol}=2778moles

Total moles = moles of solute  + moles of solvent = 9 mol + 2778 mol = 2787  

x_2 = mole fraction of solute  

=\frac{9}{2787}=3.2\times 10^{-3}

\frac{29.96-p_s}{29.96}=1\times 3.2\times 10^{-3}

p_s=29.86mmHg

Thus the vapor pressure of the solution at 29^0C is 29.86 mm Hg

5 0
3 years ago
Explain how antiacids work
ELEN [110]
They work by reducing the acid in our stomach because anti acids alkalis.
3 0
3 years ago
What color do acids turn litmus paper?
Ivanshal [37]

Answer:

red

Explanation:

........pls brainliest

8 0
3 years ago
Read 2 more answers
When 3243. grams of iron (III) chloride are reacted with 511.8 grams of hydrosulfuric acid, which is the limiting reactant?
AleksAgata [21]

Answer:

Hydrosulfuric acid will act as limiting reactant.

Explanation:

Given data:

Mass of iron(III) chloride = 3243.0 g

Mass of hydrosulfuric acid = 511.8 g

Limiting reactant = ?

Solution:

Chemical equation:

2FeCl₃ + 3H₂S       →       Fe₂S₃ + 6HCl

Number of moles of iron(III) chloride:

Number of moles = mass/molar mass

Number of moles = 3243.0 g/ 162.2 g/mol

Number of moles = 20 mol

Number of moles of hydrosulfuric acid:

Number of moles = mass/molar mass

Number of moles = 511.8 g/ 34.1 g/mol

Number of moles = 15 mol

Now we will compare the moles of both reactant with products

                      FeCl₃          :          Fe₂S₃

                       2                :            1

                      20               :          1/2 ×20 = 10

                      FeCl₃          :            HCl

                       2                :              6

                      20               :          6/2 ×20 = 60

                      H₂S             :          Fe₂S₃

                       3                :            1

                      15               :          1/3 ×15 = 5

                      H₂S            :            HCl

                       3                :              6

                      15                :          6/3 ×15 = 30

Hydrosulfuric acid producing less number of moles of product thus, it will act as limiting reactant.

 

5 0
3 years ago
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