4. Balance the following equations (show work)
a.___H2(g) +___O2(g) →___H2O(1)

b.____Fe(s) +___O2(g)→___Fe2O3(s)

c.___Al(s) +___HCl(aq) →___AlCl3(aq) +___H2(g)

d.____CaCO3(s) +____HCl(aq) →____CaCl2(aq) +____CO2(g) +____H2O(1)

Answer:

I believe it would be Law of conservation of mass (sorry if I'm incorrect)

Answer:

what do you mean?

Explanation:

Studying the brightness of a star can indeed help scientists determine what part of the life-cycle a star is in. The brightness of a star is directly related to its stage in the life cycle.The statement is true.

During the early stages of a star's life, it is formed from a cloud of gas and dust. As the star contracts under its own gravity, it starts to heat up and emits light. This is known as the protostar stage.

As the star continues to contract, it reaches a point where the core temperature becomes hot enough for nuclear fusion to occur. At this stage, the star enters the main sequence phase, where it will spend the majority of its life. The brightness of the star in this phase is determined by its mass. More massive stars are brighter than less massive ones.

As the star ages, it exhausts its hydrogen fuel in the core and begins to evolve. Depending on its mass, a star can become a red giant, a white dwarf, a neutron star, or even a black hole. Each of these stages has a different brightness profile.

By observing the brightness of a star over time, scientists can gather information about its age, mass, and evolutionary stage. This can provide insights into the star's life cycle and help in understanding the processes occurring within it.

Thus, studying the brightness of a star is an important tool for scientists to determine what part of the life cycle a star is in. By analyzing its brightness profile, scientists can gain valuable information about the star's age, mass, and evolutionary stage.The statement is true.

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Answer:

Molecule

Explanation:

Two or more atoms linked/bonded together is called a molecule.

Answer:

[tex]\huge\boxed{\sf Q = 5880\ Joules}[/tex]

Explanation:

Given:

m = mass = 40 g = 0.04 kg

c = specific heat constant of water = 4200 J/Kg°C

ΔT = change in temperature = T2-T1 = 60 °C - 25 °C = 35°C

Required:

Q = change in heat energy = ?

Formula:

Q = mcΔT

Solution:

Q = (0.04)(4200)(35)

Q = 5880 Joules

[tex]\rule[225]{225}{2}[/tex]

Answer:

name is Ian symbol is spices mass number is 100

Explanation:

#

Answer: This makes the lemonade a homogenous mixture

Explanation:

If the freshly squeezed lemonade is made by squeezing lemons to extract the sour juice and mixing this with water and sugar all the substances in the mixture finally created are in the same phase.

1,chlorine ions

2,sodium chloride

Answer:

The softball game will still go on because the "L" symbolizes a low pressure system which usually brings sunny weather.

Explanation:

Answer:

I am also beginners I don't know I am only completing this answer and sorry!!!!!!

Answer:

Solar Energy and Chemical energy

Explanation:

Answer: It would be malleable, solids, luster, conductors, reactive

Explanation:

Answer:

12. A

13. A

14. D

15. B

Explanation:

12. The 3rd law of motion is the force of our object being equal and opposite the other. If the Buller goes forward with force, the the gun recoils backwards with the same force.

13. There's nothing else described in the problem besides him getting kicked in the face

14. If you mive the oars forwards then the boat itself moves backwards

15. The gas helps push the rocket upwards since it goes downwards.

Answer:

Sodium chloride is an ionic compound which makes it stronger and have a higher melting and boiling point. Candle wax is a covalent compound so it has a low melting point.

Explanation:

Answer:

its true

Explanation:

I took the test

Answer:

Elements of the periodic table are arranged in order of increasing atomic number. the periodic law states "when elements are arranged in increasing atomic number, there is a periodic repetition of their  chemical and physical properties."

Explanation:

Answer:

5

Explanation:

Answer:

0

Explanation:

Answer:

atomic number

Explanation:

Answer:

new substances

Explanation:

Atoms of different elements can combine to make new substances. A molecule is formed when two or more atoms join together chemically. If atoms combine that are of two or more different elements, we call that a compound. All compounds are molecules, but not all molecules are compounds.

Answer:

numer 1:Neutrons are required for the stability of nuclei, with the exception of the single-proton hydrogen nucleus. Neutrons are produced copiously in nuclear fission and fusion. They are a primary contributor to the nucleosynthesis of chemical elements within stars through fission, fusion, and neutron capture processes.

number 2:The number of neutrons is equal to the difference between the mass number of the atom (M) and the atomic number (Z).let me know if i helped

Answer:

The answer would be B.

Explanation:

Answer:

Explanation:

How many cm of a solution of 0.100 mol dm NaOH are required to completely  neutralize  25.0 cm of 0.250 mol dm H3PO4?.

a) Write a balanced equation for the reaction NaOH to neutralize (4 marks

?. ) 25.0 cm of 0.250 mol dm H3PO4

H3PO4 + 3NaOH----------> Na3PO4 +3 H2O

b) How many moles of H3PO4 need to be neutralized? (1 marks)

25.0 cm3 of 0.250 mol dm3 H3PO4: 1 liter has 0.25 moles. 100 ml has 0.025 moles 25 ml has o.025/4 molea or 0.00625 moles)

c How many moles of NaOH are needed to neutralize the H3PO4? (1 marks)

for every moles of H3PO4, WE NEED 3 MOLES OF NaOH.  FOR 0.00625 MOLES WE NEED 3X 0.00625 =0.01875 MOLES OF NaOH

d) How many cm3 of 0.100 mol /l NaOH contain the moles in question 5(©) above? (1 marks)

1 L CONTAINS 0.100 Moles

100 ml contains 0.010Moles

we need 187.5 ml since (187.5 X 0.100)/1000=0.01875

Answer:

NH4Br and NH4I are both soluble in water, and they don't react with each other. So this pair will not form precipitation.

NaClO4 and (NH4)2S are both soluble in water.  While in water, they dissociate into Na+, ClO4-, NH4+ and S2- ions, which don't react with each other.  So this pair will not form precipitation.

Ni(NO3)2 and Na2CO3 are both soluble in water.  When the 2 solutions combine, NiCO3 forms.  NiCO3 is not soluble in water, so it will precipitate out from the solution. This pair will result in precipitation.

K2SO4 and Cu(NO3)2 are both soluble in water. While in water, they dissociate into K+, SO42-, Cu2+ and NO3- ions, which don't react with each other.  So this pair will not form precipitation.

Explanation:

Hope this helps...

Answer:

A transition from one accepted theory to another or from one employed method to another.

Explanation:

Answer:

beryllium chloride

Explanation:

Therefore a compound made from beryllium and chlorine will be named beryllium chloride.

As per the balanced reaction, two moles or 319.4 g of Fe₂O₃ gives 4 moles or 223.4 g of Fe. Thus 6.10 g gives 4.22 g of Fe.

What is ferric oxide?

Ferric oxide is an ionic compound formed from iron and oxygen in which iron is in  +3 oxidation state. It is also called iron oxide which decomposes to form molecular oxygen and iron.

The balanced equation giving Fe and oxygen from ferric oxide is written below:

[tex]\rm 2Fe_{2}O_{3} \rightarrow 4Fe + 3O_{2}[/tex].

The molar mass of ferric oxide is 159.7 g/mol. Thus two moles weighs 159.7 × 2 = 319.4 g. Atomic mass of Fe is 55.85 hence, 4 moles is 223.4 g.

As per the balanced reaction, 319.4 g of ferric oxide gives 223.4 g of iron. Thus mass of iron , Fe produced from 6.10 g of ferric oxide is calculated as follows:

mass of Fe = (223.4× 6.10 ) /319.4

                  = 4.226 g

Hence, 4.22 g of Fe will be produced from 6.10 g of Fe₂O₃.

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Answer:

protons: 8

neutrons: 9

Explanation:

the atomic number tells you how many protons are in a element. The mass is the number of protons + neutrons.

17 - 8 = 9 neutrons

There are 8 protons and 9 neutrons in the nucleus of the oxygen atom.

The atomic number of an atom is the number of protons in atom of an element.

It can also be defined as the number of electrons in a neutral atom of an element.

The mass number is the number of protons and neutrons in the nucleus of an atom of an element.

The proton number of the oxygen atom is 8

The neutron number is 17 - 8 = 9

Therefore, in the nucleus of the oxygen atom, there are 8 protons and 9 neutrons.

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