b- How many electrons does sodium have?

a) ionic

chlorine is present in top of group 17 and right of period 3 and

electronegativity(the tendency to gain electrons)

increases up the group and right the group.

so it has high tendency to form anion.

In the same way both Na and K are present up the group and left side and the tendency to lose electrons in both becomes high and they tend to form cation.

Answer:

They use the pH scale

Explanation:

The strong acid and strong base has high rate constant of dissociation. Weak acid and base are the one whose rate constant for the dissociation is low, they do not dissociate readily in water. Scientist use pH scale to classify substances that are either an acid or a base.

Acid is a solution which releases H⁺ hydrogen ion when dissolved in water. Base are the solution which releases hydroxide ion OH⁻ ion when dissolved in water. . At room temperature pH scale is between 0 to 14. pH of neutral solution is 7.

The pH of acid is between 0-7 on pH scale. acid turns blue litmus paper to red. Acids have sour taste and corrosive nature. Mathematically the concentration of hydrogen ion can be calculated using this formula

Mathematically,

pH=-log[H⁺]

Therefore, scientist use pH scale to classify substances that are either an acid or a base.

To know more about acid and bases, here:

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Answer:

1. chemical fertillizers encourage plant disease

2. chemical fertillizers affect micro-organism living in the soil.

Explanation:

Answer:

Mass of hydrogen produced  = 2.1 g

Mass of excess reactant left = 25.2 g

Explanation:

Given data:

Mass of Mg = 50.0 g

Mass of HCl = 75.0 g

Mass of hydrogen produced = ?

Mass of excess reactant left = ?

Solution:

Chemical equation:

Mg + 2HCl      →       MgCl₂ + H₂

Number of moles of Mg:

Number of moles = mass/molar mass

Number of moles = 50 g/ 24 g/mol

Number of moles = 2.1 mol

Number of moles of HCl:

Number of moles = mass/molar mass

Number of moles = 75 g/ 36.5 g/mol

Number of moles = 2.1 mol

now we will compare the moles of hydrogen gas with both reactant.

                     Mg       :        H₂

                       1          :       1

                     2.1         :     2.1

                   HCl         :        H₂

                      2          :          1

                    2.1          :        1/2×2.1 = 1.05 mol

HCl is limiting reactant and will limit the yield of hydrogen gas.

Mass of hydrogen:

Mass = number of moles × molar mass

Mass=  1.05 mol ×2 g/mol

Mass = 2.1 g

Mg is present in excess.

Mass of Mg left:

         HCl            :           Mg

             2             :            1

            2.1            :         1/2×2.1 = 1.05

Out of 2.1 moles of Mg 1.05 react with HCl.

Moles of Mg left = 2.1 mol - 1.05 mol = 1.05 mol

Mass of Mg left:

Mass = number of moles × molar mass

Mass = 1.05 mol × 24 g/mol

Mass = 25.2 g

Answer:

Gravity always pulls objects such as a desk, book or person down. Thus, when you jump gravity causes you to land on the ground. Friction, however, doesn't pull objects down

Answer:

See explanation

Explanation:

The phase changes of carbon dioxide is quite interesting. It is even more interesting that its phase change from gas to solid is dependent on pressure and temperature.

The triple point of CO2 is -56°C at 5.11 atm pressure. This implies that below 5.11 atm, liquid CO2 can not exist. In fact, at -78°C and 1 atm, CO2 is a solid.

Hence, when pressure increases from 1 atm to 10 atm at -40C, CO2 changes from liquid to gas.

Answer:

2.5.2 Atomistic Configurations of Oxygen in Silicon Crystals

Oxygen atoms are incorporated in the silicon lattice on an interstitial position (denoted by Oi), where the oxygen atom sits in an almost bond-centered position between two adjacent Si atoms [101]. Several of the local vibration modes are infrared (IR) active. The predominant IR line at 1104/cm (at room temperature) was calibrated with respect to other analytical methods, such as gas fusion and several radioactive techniques, and is used as the standard method for the quantitative determination of the oxygen content in as-grown silicon crystals (as-grown silicon usually contains only a negligible amount of precipitated oxygen).

Answer:

B) nitrogen

the Earth's atmosphere is mostly nitrogen

Answer:

False

Explanation:

Please mark brainlliest if you want and mark 5 stars please. Thank you and have a good day.

Answer:

Bohr models show the electrons in atoms are in orbits of differing energy around the nucleus while Dot Diagrams show the bonding in a small molecule only.

Explanation:

Answer:

Chromium is electroplated on other metals. 2. Gold is electroplated on other cheap metals.

Answer:

Q = 5671.05 J

Explanation:

Given data:

Mass of metal = 525 g

Initial temperature = 32.0 °C

Fina temperature = 43.0 °C

Heat absorbed by metal = ?

Solution:

Specific heat capacity:

It is the amount of heat required to raise the temperature of one gram of substance by one degree.

specific heat capacity of metal X = 0.982 J/g.°C

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

ΔT = 43.00°C - 32.00°C

ΔT = 11.00°C

Q = 525 g × 0.982 J/g.°C  × 11.00°C

Q = 5671.05 J

Answer:b

Explanation:

Answer:

False

Explanation:

Not all molecules are compounds, since some molecules, such as oxygen gas (above image of molecule of-O2) or ozone (O3), consist only of one element or type of atom. Water is also a molecule because it is made from atoms that have been chemically combined.

Answer:

Mass = 21.58 g

Explanation:

Given data:

Mass of MgCl₂ = 35 g

Mass of Mg(OH)₂ produced = ?

Solution:

Chemical equation:

MgCl₂ + 2KOH    →     Mg(OH)₂ + 2KCl

Number of moles of MgCl₂:

Number of moles = mass/molar mass

Number of moles = 35 g/ 95.2 g/mol

Number of moles = 0.37 mol

now we will compare the moles of MgCl₂ and Mg(OH)₂

                MgCl₂         :        Mg(OH)₂

                   1               :            1

                 0.37           :        0.37

Mass of  Mg(OH)₂ :

Mass = number of moles × molar mass

Mass = 0.37 mol × 58.32 g/mol

Mass = 21.58 g

Answer:

it is a physics questions not chemistry

Explanation:

speed=distance/time

so distance =speed * time

=120*4

=480 km

Answer:

water, work

Explanation:

The flow of electros through a conductor is electric current. These electrons cannot be seen and so electric circuits can be used to model the arrangement and understand the process. Water flowing through pipes is a fitting mechanism that looks like the electrical circuit.

In this mechanism, the pipe is seen as the wire in the electric circuit while the pump is viewed as the battery. The pressure, like the voltage generated by the battery, comes from the pump and drives the water through the pipe.

Answer:

2.27%

Explanation:

The observed value of the boiling point = 71.8°C

The actual value of the boiling point = 70.2°C

We need to find the percentage error of the student's measurement. The percentage error in any value is given by :

[tex]\%=\dfrac{\text{calculated value-actual value}}{\text{actual value}}\times 100\\\\=\dfrac{71.8-70.2}{70.2}\times 100\\\\=2.27\%[/tex]

So, the required percentage error is 2.27%.

Answer:

V₂ = 1.86 L

Explanation:

Given data:

Initial volume = 4.30 L

Initial pressure = 1 atm

Initial temperature = 273.15 K

Final temperature = 302 K

Final volume =  ?

Final pressure = 2.56 atm

Solution:

According to general gas equation:

P₁V₁/T₁ = P₂V₂/T₂

V₂ = P₁V₁T₂ /T₁ P₂

V₂ = 1 atm ×4.30 L × 302 K / 273.15 K × 2.56 atm

V₂ = 1298.6 atm.L.K / 699.26 K.atm

V₂ = 1.86 L

Answer:

Explanation:

When you are pedaling the bike, it is transforming chemical energy, supplied by the breakdown of the food you eat (any food), into mechanical energy to turn the pedals (energy we produce). The chemical energy is potential and the mechanical energy is kinetic.

Hope this helps :)

Explanation:

Hope it will help):)

Answer:

an acid is any hydrogen containing substance that. can donate protons.

a base is a molocule that is able to accept hydrogen ion from an acid

Answer:

the answer is C

Explanation:

it can form 3 bonds

Answer:

The correct answer is  - 32 cells.

Explanation:

In the meiosis type of cell cycle or cell division, a single parent cell divides into four daughter cells, unlike mitosis. Meiosis takes place in the reproductive or sex cell and called reduction division.

As we know each cell divide into four daughter cells.

1  reproductive cell = 4 daughter cells

2 reproductive cell = 8 daughter cells

Now each daughter cell undergo meiosis than each cell will produce 4 cells so,

8 daughter cells will produce:

8 *4 = 32 cells.

Thus, the correct answer is  - 32 cells.

Answer:

5 atoms are in each molecule of calcium carbonate

Answer:This pressure is transmitted throughout the liquid and makes it more difficult for bubbles to form and for boiling to take place. If the pressure is reduced, the liquid requires less energy to change to a gaseous phase, and boiling occurs at a lower temperature

Explanation:

Atmospheric Pressure and Boiling

The pressure of gas above a liquid affects the boiling point. ... If the pressure is reduced, the liquid requires less energy to change to a gaseous phase, and boiling occurs at a lower temperature

Answer:

The correct statement is;

(B) Only II

Explanation:

I) The atomic mass unit or amu which is also known as daltons which is defined as 1/12 × the mass of a carbon-12 atom, which is therefore, 1.660538921 × ⁻²⁴ grams

Therefore, the mass of 1 atom of carbon-12 = 12 amu

II) The mass of one mole of oxygen-16 is 16 grams while the mass of one mole of carbon-12 is 12 grams

The mass of 4 atoms of carbon 12 = 4 × 12 amu = 48 amu

The mass of 1 atom of oxygen-16 = 15.99491461956 amu

Therefore, the mass of 3 atoms of oxygen-16 = 3 × 15.99491461956 = 47.9847438587 amu ≈ 48 amu

Therefore only II is correct.

Answer:

Carbon

Explanation: