Why did improvements in agriculture lead to the growth of cities?

If u pass a curve of 3A in a time of 90mins. how much mg will be deposited.

Maslowich

Answer:

$\boxed{\text{2.0 g}}$

Explanation:

1. Write the equation for the half-reaction.

Mg²⁺ + 2e⁻ ⟶ Mg

The number of electrons transferred (z) is 2 mol per mole of Mg.

2. Calculate the number of coulombs

Q = It

$\text{t} = \text{90 min} \times \dfrac{\text{60 s}}{\text{1 min}} = \text{5400 s}\\\\Q = \text{3 C/s} \times \text{ 5400 s} = 16 000 C$

3. Mass of Mg

We can summarize Faraday's laws as

$m = \dfrac{QM}{zF}\\\begin{array}{rcl}m & = &\dfrac{16 000 \times 24.30}{2 \times 96 485}\\& = & \textbf{2.0 g}\\\end{array}\\\text{The mass of Mg deposited is }\boxed{\textbf{2.0 g}}$

8 0

3 years ago

What is the the formula for the compound cobalt(II) phosphate.

Lena [83]

Cobalt(II) has a charge of 2+
Phosphate has a charge of 3-

Because it's an ionic compound, you will need to take the charge and make them subscripts.

The formula for cobalt(II) phosphate is Co₃(PO₄)₂

Your answer is
$\sf{Co_3(PO_4)_2}$

3 0

4 years ago

A 1300 mL sample of gas with a molar mass of 71.0 g/mol at STP has what density?

Blizzard [7]

Answer:

0.055g/mL

Explanation:

Data obtained from the question include:

Molar Mass of the gass sample = 71g/mol

Volume of the gas sample = 1300 mL

Density =?

The density of a substance is simply mass per unit volume. It is represented mathematically as:

Density = Mass /volume.

With the above equation, we can easily obtain the density of sample of gas as illustrated below:

Density = 71g / 1300 mL

Density = 0.055g/mL

Therefore, the density of the gas sample is 0.055g/mL

6 0

3 years ago

Choose all the answers that apply. Which of the following are essential elements are the most abundant on earth and are essentia

Lynna [10]

Answer:

you answers are sodium and chloride oxygen

Explanation:

sodium

chloride oxygen

8 0

3 years ago

Characterize each process as a physical change or a chemical change: (a) making ice cubes; (b) burning natural gas; (c) silver j

aniked [119]

Answer:

Explanation:

Physical change -

It refers to any change during any process , where there is no new substance is formed , is referred to as a physical change.

Any change in the state of matter is characterised under physical change.

Chemical change -

It refers to any change in a chemical process , where there is formation of any new substance , is referred to as a chemical change .

From the options given in the question,

The physical change are -

(a) making ice cubes - as there is state change from liquid to solid.

(d) a pile of snow melting - as, there is state change from solid to liquid.

The chemical change are -

(b) burning natural gas - since a chemical reaction takes place , where the natural gas reacts with oxygen.

(c) silver jewelry tarnishing - as chemical reaction takes place.

(e) baking bread - batter is converted to bread , hence there is formation of new substance.

7 0

3 years ago