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3 years ago

Melissa uses a sunscreen with an spf rating of 20. what does this does this mean?

1 answer:

4 0

If the SPF rating is 20 then it means it would provide 20 times the protection instead of no sunscreen and 20 times longer someone would take before the person started to burn or in this case 200 minutes.

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This graduated cylinder has numbers representing milliliters. A student says that the volume of the liquid inside is 21.8 millil

GaryK [48]

Explanation:

The answer for this question depends on the type of meniscus in the cylinder. If it is an upright meniscus like in water, the reading should be taken at the bottom of the meniscus. However if it is an inverted meniscus like in mercury, the reading should be taken at the top of the meniscus.

(Can you check and see if there's any pictures or information that is missing?)

3 0

2 years ago

a sample of an oxide of antimony (sb) contain 19.75 g of antimony combine with 6.5 g of oxygen . what is the simplest formula fo

frez [133]

Explanation:

The given data is as follows.

Mass of antimony = 19.75 g

Molar mass of Sb = 121.76 g/mol

Therefore, calculate number of moles of Sb as follows.

Moles of Sb = $\frac{mass}{\text{molar mass}}$

= $\frac{19.75 g}{121.76 g/mol}$

= 0.162 mol

Mass of oxygen given is 6.5 g and molar mass of oxygen is 16 g/mol. Hence, moles of oxygen will be calculated as follows.

Moles of oxygen = $\frac{mass}{\text{molar mass}}$

= $\frac{6.5 g}{16 g/mol}$

= 0.406 mol

Hence, ratio of moles of Sb and O will be as follows

Sb : O

$\frac{0.162}{0.162} : \frac{0.406}{0.162}$

1 : 2.5

We multiply both the ratio by 2 in order to get a whole number. Therefore, the ratio will be 2 : 5.

Thus, we can conclude that the empirical formula of the given oxide is $Sb_{2}O_{5}$ .

4 0

3 years ago

2NO(g) N2(g) + O2(g); Keq = 2.1 × 1030 What does the value of the equilibrium constant indicate?

olga_2 [115]

The equilibrium constant is a value which represents the equilibrium of a reaction. It is a reaction quotient when the reaction reached equilibrium. If Keq is greater than 1, the mixture contains mostly the products. On the other hand, if Keq is less than 1, the mixture contains the reactants. For this case, the mixture contains mostly products.

7 0

3 years ago

When a substance was dissolved in water, the temperature of the water increased. This process is described as

NemiM [27]

The correct answer will be A

3 0

3 years ago

How many valence electrons are in an atom of phosphorus? (atomic number 15) (1 point)?

densk [106]

There are 5 valence electrons in a atom of phosphorus.

5 0

3 years ago