pls help with these question because I don't understand what are pure substance and how to tell ​

Answer: oxygen

Explanation: because we need it to live ;)

Answer:

(2) oxygen

Explanation:

Answer: The chemical formulas of calcium and magnesium chloride are [tex]CaCl_2[/tex] and [tex]MgCl_2[/tex]

Explanation:

A chemical formula is the representation of a substance in terms of chemical symbols showing the elements present in a compound and their relative proportion.

Calcium is having an atomic number of 20 has electronic configuration of [tex]1s^22s^22p^63s^23p^64s^2[/tex]. It can lose two electrons to have an oxidation state of +2.

Magnesium is having an atomic number of 12 has electronic configuration of [tex]1s^22s^22p^63s^2[/tex]. It can lose two electrons to have an oxidation state of +2.

Chlorine is having an atomic number of 17 has electronic configuration of [tex]1s^22s^22p^63s^23p^5[/tex]. It can gain one electron to have an oxidation state of -1.

Thus the chemical formulas of calcium and magnesium chloride are [tex]CaCl_2[/tex] and [tex]MgCl_2[/tex]

Answer:

Positive

Explanation:

For the most effective hot pack, the temperature change should be positive.

Hot packs are generally utilized for their heat-producing abilities. Hence, the reactions leading to the activation of hot packs are usually exothermic, that is, heat energy generating. In other words, positive or increased temperatures must be generated when hot packs are activated.

This is unlike cold packs which are utilized for the cold-generating abilities. Reactions leading to their activations must be endothermic, that is, heat-absorbing.

Answer:

a

Explanation:

because look at the pic of the flower

Answer:

a

Explanation:

Answer:

the concentration of hydrochloric acid

the temperature in heating

Answer:

10460J

Explanation:

Given parameters:

Mass of water sample  = 100g

Initial temperature = 35°C

Final temperature  = 60°C

Unknown:

Amount of energy absorbed by water = ?

Solution:

The amount of energy absorbed by water is mathematically expressed below;

    H  = m C ΔT

H is the amount of energy

m is the mass

C is the specific heat capacity of water  = 4.184J/g°C

ΔT  = 60°C  - 35°C  = 25°C

 Now insert the parameters and solve;

 H = 100 x 4.184 x 25  = 10460J

Answer:

1 mole of any gas at STP occupies 22.4 liters of volume. Using this information, the volume occupied by any number of moles (or grams) can be determined.

Explanation:

There will be 22.4 liters of oxygen, which will be 5.00 moles of oxygen occupied at STP.

The International System of Units uses the mole (symbol: mol) as the unit of material quantity. How many elementary entities of a particular substance are present in an object or sample is determined by the quantity of that material.

The chemical element with the atomic number 8 and symbol O is called oxygen. It belongs to the periodic table's chalcogen group, is a very reactive nonmetal, and is an oxidizing agent that easily produces oxides with most elements as well as other compounds.

1 mole of any gas at STP occupies 22.4 liters of volume. Using this information, the volume occupied by any number of moles (or grams) can be determined.

Therefore, at STP, 5.00 moles of the available 22.4 liters of oxygen will be occupied.

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Answer:

M=3

B=25

Equation= 3x+25

Explanation:

M is your slope and if you follow the slope- intercept formula (y=m+b) you just need to plug in the numbers.

Thus your answer:

M=3

B=25

Equation= 3x+25

Answer:

Probably the one you are already dating...

Explanation:

...but if you really like the other guy then you should chose him.

Answer:

When you combine the solid (baking soda) and the liquid (vinegar), the chemical reaction creates a gas called carbon dioxide. Carbon dioxide is invisible, except as the bubbles of gas you may have noticed when the vinegar and baking soda mixture began to fizz.

Explanation:

Answer:

two hydrogen atoms

In chemical equations, the number of atoms of each element in the reactants must be the same as the number of atoms of each element in the products. If we count the number of hydrogen atoms in the reactants and products, we find two hydrogen atoms.

Can i get brainlisted please

Answer:

two hydrogen atoms.

Explanation:

the number of atoms of each element in the reactants must be the same as the number of atoms of each element in the products. If we count the number of hydrogen atoms in the reactants and products, we find two hydrogen atoms.

hope it helps : )

Answer:

The ionic compound NaCl has a Face Centered Cubic unit cell

The site for atoms are Face, center and Edges corner.

Effective number of atoms

Na+

1centers + 12edges x[tex]\frac{1}{4}[/tex] = 4 Na+  

Cl-

6face x[tex]\frac{1}{2}[/tex]  + [tex]\frac{1}{8}[/tex] x8 corners = 4Cl-

This is just one unit cell effective atom, there are thousand's of such unit cells are combined to form one such structure of NaCl. The real formula of NaCl is Na4Cl4 but for simplicity we use empirical formula that is NaCl.

Answer:C

Explanation:

Because they use it so that they can find more information about it.

What scientists use to describe a constellation: C. It’s star pattern

A star is a giant astronomical or celestial object that comprises a luminous sphere of plasma and bounded together by its own gravitational force.

Generally, a star is typically made up of two (2) main hot gas and these are Hydrogen (H) and Helium (He).  Some examples of a star are;  

A galaxy can be defined as a collection (group) of many billions of stars, which are existing independently. Thus, the greatest number of stars are found in a galaxy.

A constellation can be defined as a collection (group) of visible stars forming a recognizable or perceived pattern in the sky. Also, this pattern or outline is sometimes attributed by scientists to a mythological figure.

In conclusion, scientists use the pattern of a star to describe a constellation.

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Explanation:

Neutron - no charge, located in the nucleus.

electron - - charge, located outside the nucleus.

Quark- smallest theoretical particles of protons and neutrons.

proton- + charge, located in the nucleus.

Answer:

The electrons are supplied by the species getting oxidized. They move from anode to the cathode in the external circuit. The external battery supplies the electrons. They enter through the cathode and come out through the anode

The electrons are supplied by the species getting oxidized. They move from the anode to the cathode in the external circuit.

An electron is a negatively charged subatomic particle.

The reaction at the anode is oxidation and that at the cathode is reduction. Here, the anode is positive and the cathode is the negative electrode. The reaction at the anode is oxidation and that at the cathode is reduction.

The electrons are supplied by the species getting oxidized. They move from the anode to the cathode in the external circuit. The external battery supplies the electrons. They enter through the cathode and come out through the anode.

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Answer:

Heat, Q = 262 kJ

Explanation:

Given that,

Mass of a sample, m = 750 g

Initial temperature, [tex]T_i=95^0\ C[/tex]

Final temperature, [tex]T_f=17^0\ C[/tex]

The specific heat of the sample, [tex]c=4.18\ J/g^0 C[/tex]

We need to find the amount of heat released. The amount of heat released is given by the formula as follows :

[tex]Q=mc\Delta T\\\\Q=750\times 4.48\times (17-95)\\\\Q=-262080\ J\\\\Q=-262\ kJ[/tex]

So, 262 kJ of heat is released by the sample.

Answer:

A

Explanation:

learned this in biology

Answer:

16

Explanation:

hope you like the answer

Answer:

4NO2 + 2Na2O + O2 → 4NaNO3

Answer:

I think you meant metabolism

Explanation:

me·tab·o·lism

the chemical processes that occur within a living organism in order to maintain life.

Answer: I’m guessing you meant metabolism. Metabolism is the chemical reactions in the body's cells that change food into energy. Our bodies need this energy to do everything from moving to thinking to growing. Specific proteins in the body control the chemical reactions of metabolism.

Answer:

. Increasing the volume of the container

Explanation:

Answer:

The kinetic energy of the molecules  

increases

.

The speed of the molecules  

increases

.

The density of the fluid  

decreases

.

The fluid  

rises

.

Explanation:

this is correct on edge

When the temperature of a fluid increases, then the kinetic energy of the molecules INCREASES, the speed of the molecules INCREASES, the density of the fluid DECREASES, and the fluid RISES.

In conclusion, when the temperature of a fluid increases, then the kinetic energy of the molecules INCREASES, the speed of the molecules INCREASES, the density of the fluid DECREASES, and the fluid RISES.

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Answer:

Partial pressure of gas = 0.913 mmHg

Explanation:

Since the column of water in the tube is higher than in the container, it means that the atmospheric pressure is greater than the gas pressure.

Also, since the gas is collected over water, the total gas pressure is due to partial pressure of the gas and the partial pressure of water vapor, i.e.,

Hence, Partial pressure of gas = Patm - Pressure due to height of water column - Partial pressure of water

Pressure due to height of water column = 55 mmH₂O

Since 13.595 mmH₂O = 1 mmHg

55 mmH₂O = 55/13.595  mmHg

Converting to 55/13.595  mmHg to atm

Pressure due to height of water column = (55/13.595  mmHg) * (1 atm/760 mmHg) = 0.00532

Partial pressure of gas = (0.950 - 0.00532 - 0.0313) atm

Partial pressure of gas = 0.913 mmHg

Answer:

1. small intestine: digestive system

2. blood vessels: cardiovascular system

3. lungs: respiratory system

4. tricep: muscular system

5. spine: skeletal system

Answer:

1. small intestine: digestive system

2. blood vessels: cardiovascular system

3. lungs: respiratory system

4. tricep: muscular system

5. spine: skeletal system

Explanation:

Answer:

ummmmmmmmmmmmmmmmmmmmmmmm

Answer:

????????????

Explanation:

ummmmmmmmm