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makvit [3.9K]
3 years ago
13

Help please thank you

Chemistry
1 answer:
Vikki [24]3 years ago
8 0

Answer:

B I think I am pretty sure

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How many grams of agarose would you add to make 50ml of a 2 percent gel? why?
vodka [1.7K]
About 1 gram. 1 part of 50 is 2%
8 0
3 years ago
How many molecules of N204 are in 85.0 g of N2O4?
alukav5142 [94]

Answer:

5.56 × 10^23 molecules

Explanation:

The number of molecules in a molecule can be calculated by multiplying the number of moles in that molecule by Avagadro's number (6.02 × 10^23)

Using mole = mass/molar mass

Molar mass of N2O4 = 14(2) + 16(4)

= 28 + 64

= 92g/mol

mole = 85.0/92

= 0.9239

= 0.924mol

number of molecules of N2O4 (nA) = 0.924 × 6.02 × 10^23

= 5.56 × 10^23 molecules

4 0
3 years ago
The cylinder of aluminum in class was approximately 13mm in circumference and 42mm in length. What would be it's approximate mas
Roman55 [17]

Answer:

Mass, m = 1.51 grams

Explanation:

It is given that,

The circumference of Aluminium cylinder, C = 13 mm = 1.3 cm

Length of the cylinder, h = 4.2 cm

We know that the density of the Aluminium is 2.7 g/cm³

Circumference, C = 2πr

r=\dfrac{C}{2\pi}\\\\r=\dfrac{1.3}{2\pi}\\\\r=0.206\ cm

Density is equal to mass per unit volume.

d=\dfrac{m}{V}

m is mass of the cylinder

V is the volume of the cylinder

V=\pi r^2h\\\\V=\dfrac{22}{7}\times0.206^2\times 4.2\\\\V=0.5601\ cm^3

So,

m=d\times V\\\\m=2.7\times 0.5601\\\\m=1.51\ g

So, the mass of the cylinder is 1.51 grams.

5 0
3 years ago
What causes a water strider to be able to walk on water?
Lena [83]

Answer:

By repelling water, the tiny water striders stand on the water's surface and the captured airs allows them to float and move easily.  so number 2. Surface Tension.

Explanation:

The attraction between water molecules creates tension and a very delicate membrane. Water striders walk on this membrane. ... The legs have tiny hairs that repel water and capture air.

8 0
3 years ago
Read 2 more answers
What is the pH of a solution with an [H+] of (a) 5.4 x 10-10, (b) 4.3 x 10-5, (c) 5.4 x 10-7?
IgorLugansk [536]

Answer:

a. 9.2

b. 4.4

c. 6.3

Explanation:

In order to calculate the pH of each solution, we will use the definition of pH.

pH = -log [H⁺]

(a) [H⁺] = 5.4 × 10⁻¹⁰ M

pH = -log [H⁺] = -log 5.4 × 10⁻¹⁰ = 9.2

Since pH > 7, the solution is basic.

(b) [H⁺] = 4.3 × 10⁻⁵ M

pH = -log [H⁺] = -log 4.3 × 10⁻⁵ = 4.4

Since pH < 7, the solution is acid.

(c) [H⁺] = 5.4 × 10⁻⁷ M

pH = -log [H⁺] = -log 5.4 × 10⁻⁷ = 6.3

Since pH < 7, the solution is acid.

3 0
2 years ago
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