please help me i’m struggling

Answer:

after 4 half-lives, 125g is left

Explanation:

The half-life of a radioactive substance is the time it takes for the substance to decay by half its original mass.

In this example, we are asked to find the remaining mass after four half-lives.

What we will simply do is to reduce the starting mass by half, after each half-life decay. this is done as follows:

1st half-life decay: starting mass 2000g

final mass = 2000g ÷ 2 = 1000g

2nd half-life decay: starting mass = 1000g

final mass = 1000 ÷ 2 = 500

3rd half-life decay: starting mass = 500

final mass = 500 ÷ 2 = 250g

4th half-life decay: starting mass = 250g

final mass = 250 ÷ 2 = 125g

∴ after 4 half lives, 125g is left

Answer:

Explanation:

A property closely related to an atom's mass number is its atomic mass. The atomic mass of a single atom is simply its total mass and is typically expressed in atomic mass units or amu.

Answer:

F = 1000 g cm/s²

Explanation:

Let the weight of 1 ball is 50 gram

Acceleration, a = 20 cm/s²

We need to find the force exerted by a golf ball. We know that,

F = ma

So,

F = 50 g × 20 cm/s²

F = 1000 g cm/s²

So, the required force is 1000 g cm/s².

Answer:

2.38x10²³ atoms oxygen

Explanation:

To solve this question we need to convert the mass of sand to moles using its molar mass (Molar mass SiO₂ = 60.08g/mol). Twice these moles are the moles of Oxygen and using Avogadro's number we can find the amount of atoms of Oxygen in the mixture:

Moles SiO₂:

11.87g * (1mol / 60.08g) = 0.1976moles SiO₂

Moles Oxygen:

0.1976moles SiO₂* 2 = 0.3951moles oxygen

Atoms oxygen:

0.3951moles oxygen * (6.022x10²³atoms / 1mol O₂) =

Answer:

D - combining it's potential energy with it's kinetic energy

Answer:

glucose ethanol and co2

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Answer:

In anaerobic respiration yeast breaks down glucose, forming ethanol and carbon dioxide as its waste products. When the glucose is nearly used up, and provided that oxygen is present, yeast uses the ethanol as a respiratory substrate to produce carbon dioxide and water in aerobic respiration.

Explanation:

Hope it is helpful....

Answer:

An energy pyramid shows the flow of energy at each trophic level in an ecosystem. A pyramid shape is used because energy is lost at each trophic level when organisms use it up.

Explanation:

Answer: b

Explanation:

Answer:

C: electrons is the 3s orbital are higher than those in the 2s orbital

Explanation:

Looking at the options, the correct one is that the electrons in the 3s orbital will possess more energy than those in the 2s orbital. This is because the the 2s orbitals will be filled with electrons first before the 3s orbital.

Also from basics we know that the energy of an orbital increases as the quantum number increases.

Answer:

3.57moles

Explanation:

The number of moles in a compound can be got from the number of molecules it contains.

Since;

number of moles (n) = number of molecules (nA) ÷ Avagadro's number

Avagadro's number = 6.02 × 10^23 molecules

H20 contains 2.15 x 10^24 molecules, according to this question. Therefore,

n = 2.15 x 10^24 ÷ 6.02 × 10^23

n = 0.357 × 10^(24-23)

n = 0.357 × 10^1

n = 3.57moles

Hence, 3.57moles are present in in 2.15 x 10^24 molecules of H2O.

Answer:

A

Explanation:

Answer:

White light is made of a spectrum of various colors.

Explanation:

As light passes through a prism, it is bent, or refracted, by the angles and plane faces of the prism and each wavelength of light is refracted by a slightly different amount. ... As a result, all of the colors in the white light of the sun separate into the individual bands of color characteristic of a rainbow.

Answer:

wind is just high and low pressure of air, when a high pressure comes and crashes into a low pressure air pocket than it can form a wind storm.

Explanation:

The Uneven heating of the Earth's surface. Earth's rotation and unequal heating of the Earth's surface. air pressure towards regions of lower air pressure. ... air moving from areas of high pressure to areas of low pressure.

This is what will most likely cause a sudden wind to start blowing.

Answer:

2

Explanation:

2AgNO3 + Cu -----> Cu(NO3)2. + 2Ag

Answer: The four ions formed are [tex]H^+[/tex] , [tex]OH^-[/tex] , [tex]Na^+[/tex] and [tex]Cl^-[/tex]

Explanation:

Electrolysis is the process where electricity is used to drive chemical reactions.

In the electrolysis of aqueous solution of sodium chloride, hydrogen gas produces at the cathode which is a negative electrode and chlorine gas produces as the anode which is a positive electrode and the sodium hydroxide remains dissolved in the solution.

The reactions will be :

[tex]NaCl\rightarrow Na^++Cl^-[/tex]

[tex]H_2O\rightarrow H^++OH^-[/tex]

Hence, electrolysis of an aqueous solution of sodium chloride lead to the formation of four ions,[tex]H^+[/tex] , [tex]OH^-[/tex] , [tex]Na^+[/tex] and [tex]Cl^-[/tex]

Answer:

yes I do I feel like people think that people's are thinking that men are stronger then women in someone situations

Answer:

yes

Explanation

i would say yes because many woman and girls struggle to get jobs because of their record,hair,skin color,and past.

Answer:

it's sensitivity

Explanation:

because it's the action of sensing and reacting to something

also it was process of elimination

Explanation:

Hydrogen = H

Nitrite = NO₂⁻

The compound formed by Hydrogen and Nitrite is;

Name = Nitrous Acid

Formular = HNO₂

Answer:

A protein is a polymer that is made of amino acids.

Answer:

The organism in the food chain responsible for transforming radiant energy into chemical energy is;

Grass

Explanation:

Radiant energy is the energy present in electromagnetic waves which carry photons that may be considered as energy packets. It is an energy present in the Sunlight, which is an electromagnetic waves, and it is the energy in the electromagnetic waves that plants convert to chemical energy for food in the process known as photosynthesis as follows;

6CO₂ + H₂O + Radiant energy → C₆H₁₂O₆ + 6O₂

Therefore the organism in the food chain responsible for transforming radiant energy into chemical energy is the plant, grass

Answer:

10.5 dm3 O2

0.94 moles de MgO

Explanation:

La pregunta dice explícitamente que el magnesio es puro en un 90%.

Por lo tanto, masa de magnesio puro = 90/100 * 25G = 22,5 g

Número de moles de Mg = 22,5g / 24g/mol = 0,94 moles de Mg

La ecuación de reacción es;

2Mg (s) + O2 (g) ------> 2MgO (s)

Si 2 moles de Mg reaccionan con 1 moles de O2

0.94 moles de Mg reacciona con 0.94 * 1/2 = 0.47 moles de O2

Si 1 mol de O2 ocupa 22,4 dm3

0.47 moles de O2 ocupan 0.47 * 22.4 / 1 = 10.5 dm3

También;

2 moles de Mg producen 2 moles de MgO

Entonces, 0.94 moles de Mg producen 0.94 moles de MgO

Answer:

3000 Nm^2

Explanation:

We must remember that pressure is defined as force per unit area.  

We have been given the following information in the question;

Area of the tank= 1.5 m^2

Weight of water in the tank = 4500N

And;

P = F/A

F= force

A = area

P = 4500 N/1.5m^2

P= 3000 Nm^2

Answer:

first of all is that really chemistry

Answer:

False

Explanation:

Answer:

true

Explanation:

sleet is snow and rain witch are water particles and ice particles

Answer:

Carbon and Hydrogen

Explanation:

So the C stands for Carbon and H is for Hydrogen. Methane (CH4) is made up of one atom of Carbon and 4 atoms of Hydrogen.

Hope this helps

Answer: This is simple, if it has a high flammability, and you light it on fire, then that would be a chemical change.

Explanation:

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for the first one it is B OR THE SECOND OPTION