A student mixes two chemicals in a test tube. She notices that the mixture starts to bubble and the test
tube feels very warm. The student most likely concludes that the mixture is-
F. a chemical reaction that happened too quickly.
G. an endothermic reaction that absorbed thermal energy.
H. an exothermic reaction that released thermal energy.
J. not a chemical reaction.

Answer:

The answer is: Atomic radii decreases from left to right across a period and increases from top to bottom in a group.

Explanation:

Answer:

λ = 0.1 nm

E = 2 × 10⁻¹⁵ J

Explanation:

Step 1: Given data

Frequency of X-rays (ν): 3 × 10¹⁸ s⁻¹

Step 2: Calculate the wavelength (λ) of a photon of X-rays

We will use the following expression.

c = λ × ν

where,

c: speed of light

λ = c / ν

λ = (3.00 × 10⁸ m/s) / 3 × 10¹⁸ s⁻¹

λ = 1 × 10⁻¹⁰ m × (10⁹ nm/1 m) = 0.1 nm

Step 3: Calculate the energy (E) of a photon of X-rays

We will use the following expression.

E = h × ν

where,

h: Planck's constant

E = 6.63 × 10⁻³⁴ J.s × 3 × 10¹⁸ s⁻¹

E = 2 × 10⁻¹⁵ J

414 kJ energy is required to melt 2 kg of copper. Hence, option B is correct.

Energy is the capacity for doing work.

Given parameters:

Mass of copper  = 2kg

Unknown:

Amount of energy required to melt the copper  =?

Solution:

To solve this problem, we use:

Q  = m L

m is the mass

L is the latent heat of fusion of copper  = 207kJ/kg

So;

Q = 2 x 207  = 414kJ

Hence, option B is correct.

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Answer:

Hydrogen gas (H2) is a molecule, but not a compound because it is made of only one element. Water (H2O) can be called a molecule or a compound because it is made of hydrogen (H) and oxygen (O) atoms.

Explanation:

Hope this helped!!!

-BB

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Answer:

It's an element. :)

Explanation:

Answer:

In all of the ecoregions, wind and rain can weather and erode the landforms and soil. Rivers are also

powerful weathering and erosion agents. They can cut into rock and form canyons. When rivers deposit

eroded material, they change their shape or extend the shoreline. When waves along coastlines deposit

sediment, they extend beaches; when they wash sediment away, the waves erode beaches. Rivers, rock

formations, soils, topography, and precipitation in an ecoregion will determine how the processes of

weathering, erosion, and deposition work to reshape it.

Explanation:

Answer: The moles of nitrogen dioxide produced are 96.3

Explanation:

According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number [tex]6.023\times 10^{23}[/tex] of particles.

To calculate the moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given volume}}{\text {Molar volume}}=\frac{3714L}{22.4L}=165.8moles[/tex]

[tex]4NH_3(g)+7O_2(g)\rightarrow 4NO_2(g)+6H_2O(g)[/tex]

According to stoichiometry:

7 moles of oxygen [tex](O_2)[/tex] produce = 4 moles of nitrogen dioxide [tex](NO_2)[/tex]

Thus 168.5 moles of oxygen [tex](O_2)[/tex] will produce = [tex]\frac{4}{7}\times 168.5=96.3[/tex] moles of nitrogen dioxide [tex](NO_2)[/tex]

The translation of the question is

250 g of alcohol have been put in a glass together with 2 g of iodine, which dissolve completely. Calculate the concentration of the solution in% by mass?

Answer:

The %mass by mass of the given solution is 0.794%

Explanation:

We are given

Mass of solute(Iodine) = 2g

Mass of the solvent (Alcohol) = 250g

Since the Iodine dissolves completely in Alcohol

Total mass of the solution = 250 + 2 = 252g

the formula of concentration of the solution in  % by  Mass is given by

%[tex]\frac{w}{W} = \frac{Mass of the solute*100}{Total mass of the solution}[/tex]

%w/W = [tex]\frac{2*100}{252}[/tex]

          = 0.794%

Therefore the %mass by mass of the given solution is 0.794%

Answer:

that is a false sentence

Answer:

I'm sure you've already finished the est but the real answer is true, I took the k12 test and got that one correct, hope this helps anyone!

Explanation:

Answer:

C based on the number 5, which is easy to use  in calculations

Explanation:

The SI unit system is not based on the number 5.

Answer:

2.11 * 10^3 molecules of phosphoric acid

Explanation:

Answer:

Moles of tin = 0.37 mol

Explanation:

Given data:

Mass of tin oxide = 50 g

Moles of tin = ?

Solution:

Number of moles of SnO:

Number of moles = mass/molar mass

Number of moles = 50 g/ 134.71 g/mol

Number of moles = 0.37 mol

We can see there is only one mole of Sn is present in one mole of tin oxide.

Thus in 0.37 mol  of tin oxide,

0.37 mol × 1 = 0.37 mol of tin

Answer:

chemical energy

Explanation:

Answer:

clouds?

Explanation:

im sorry i just wanted the 23 points

Answer:

The longer it takes to orbit the sun.

Explanation:

Answer: 60.117 g

Explanation: [tex]1.5 mol Ca = \frac{40.078g/mol}{1mol}[/tex] multiply and quit all "mol" and you get the grams

Answer:

Explanation:Once energy is added to water by heat from the sun, the bonds between the water molecules gain kinetic energy or energy in motion. Then they escape the surface of the liquid and become a gas (water vapor), which rises into atmosphere.

Answer:

1 has the highest density because it has the most amount of circles in the least amount of space- it is the most densely filled with circles; it is the most dense.

Answer:

image 1 would have the highest density

Explanation:

the closer the molecules are the more solid an object is. if the molecules are far apart and rarely bump into eachother, it is more gaseous. the object in the middle (2) is a liquid

Answer:

a liquid with weak intermolecular forces and a high temperature

Explanation:

According to encyclopedia Britannica, "Vapour pressure is a measure of the tendency of a material to change into the gaseous or vapour state, and it increases with temperature. The temperature at which the vapour pressure at the surface of a liquid becomes equal to the pressure exerted by the surroundings is called the boiling point of the liquid."

This implies that the vapour pressure of a liquid tends to increase as the temperature of the liquid increases. Recall that vapour pressure also depends on the magnitude of intermolecular forces. The greater the magnitude of intermolecular forces, the lower the vapour pressure hence water has very much higher vapour pressure than ethane.

Answer:

A liquid with weak  intermolecular forces and a high temperature

Explanation:

I just took the test and got it right

an expert in or student of meteorology; a weather forecaster.

If there are 5 protons, there should be 5 electrons as well. Boron as an electron configuration of 2-3 or 1s2 2s2 2p.

The term proton is defined as a subatomic particle found in the nucleus of every atom. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron.

The protons are considered as elementary particles. The protons are called to be composite particles, containing three valence quarks, and together with neutrons are now classified as hadrons.

Boron has an atomic number of 5. In which it has 5 protons. Therefore, the atom also has 5 electrons. Its atomic mass is 10.811. Thus, it has 11 total particles in its nucleus i.e., protons and neutrons.

Thus,If there are 5 protons, there should be 5 electrons as well. Boron as an electron configuration of 2-3 or 1s2 2s2 2p.

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Answer:

i don't knoblol

Explanation:

i don't know lol

Answer:

a compound of high molecular weight derived either by the addition of many smaller molecules, as polyethylene, or by the condensation of many smaller molecules with the elimination of water, alcohol, or the like, as nylon. a compound formed from two or more polymeric compounds.

Explanation:

HOPE IT HELPS YOU:))

Explanation:

Hydrochloric acid is HCl.

Hydrogen is H2.

Mole ratio is the numbers infront of them, which is 6 : 3.

Answer:Hydrochloric acid is HCl.

Hydrogen is H2.

Explanation:

Answer:

...............

Answer: 1 gallon

Explanation:

Answer:

1 gallon

Explanation:

because gallons are constisting of cups and 1 cup wont be enough for a fish to swim

Answer:

Mass = 26.58 g

Explanation:

Given data:

Mass of lithium nitride = 12.87 g

Mass of lithium hydroxide produces = ?

Solution:

Chemical equation:

Li₃N + 3H₂O     →    3LiOH + NH₃

Number of moles of of Li₃N:

Number of moles = mass/molar mass

Number of moles = 12.87 g/ 34.83 /mol

Number of moles = 0.37 mol

now we will compare the moles of lithium nitride  with lithium hydroxide.

                  Li₃N            :            LiOH

                     1                :             3

                 0.37              :           3/1×0.37 = 1.11 mol

Mass of LiOH:

Mass = number of moles × molar mass

Mass = 1.11 mol × 23.95 g/mol

Mass = 26.58 g

Answer:

The alteration of the rate of the chemical reaction by the addition of a catalyst will change the dimension of L

Explanation:

The parts of the Energy profile of a reaction diagram the given letters represent are;

K = The energy possessed by the reactants

L = Activation energy required for the reaction to take place

M = Energy threshold required for the reaction to take place

N = The change in the enthalpy from the reactants to the products, which is also the energy released

O = The energy possessed by the products

The addition of a catalyst changes the route with which the reaction takes place such that the reaction rate is increased because the activation energy, L, is reduced.

Therefore, the dimension that will be changed if the rate of reaction were to be altered by a catalyst is L.