Which of the following statements are true?
1. The number of protons in an element is always the same for all
neutral atoms of that element.
II. The number of electrons in an element is always the same for all
neutral atoms and ions of that element. .
III. The number of neutrons in any element is always equal to the
number of protons of that element.
IV. The number of neutrons in an element can sometimes vary -
resulting in the formation of an unstable isotope that is
slightly
more (or less) massive than the stable atom of the same element.

Double Covalent Bond

Answer:

A Scientific Law

Explanation:

'When a substance goes through a chemical change the amount of mass and matter cannot be created nor destroyed.' This a statement of The Law of Conservation of Mass. This Scientific Law is simply titled as a law because every time experimented, the results are predictable and is natural occurrence.

Answer: I don't know if this helps but here's some information I think might help.

Usually, cells will take between 5 and 6 hours to complete S phase. G2 is shorter, lasting only 3 to 4 hours in most cells. In sum, then, interphase generally takes between 18 and 20 hours. Mitosis, during which the cell makes preparations for and completes cell division only takes about 2 hours. Calculate the percentage of time spent in each phase by counting the total number of cells in each phase (total in interphase, in prophase, etc.) and dividing each by the total number of cells you counted. How do cancer cells differ in total time required for mitosis? Cancer cells produce 117 minutes faster than regular cells. ... Normal cells require 640 minutes during interphase, cancer cells only need 380. For prophase, cancerous cells need 15 minutes less than regular cells. Another hallmark of cancer cells is their "replicative immortality," a fancy term for the fact that they can divide many more times than a normal cell of the body. In general, human cells can go through only about 40-60 rounds of division before they lose the capacity to divide, "grow old," and eventually die 3.

The answer is B

HF, because both fluorine and hydrogen are capable of forming only one covalent bond.

The formula for a compound made from fluorine and hydrogen is HF, because both fluorine and hydrogen are capable of forming only one covalent bond. The correct option is option B.

Chemical Compound is a combination of molecule, Molecule forms by combination of element and element forms by combination of atoms in fixed proportion. Covalent  bond is weaker than ionic bond.

There are two types of chemical compound one is covalent compound and other is ionic compound, covalent compound formed by sharing of electron and ionic compound formed by complete transfer of electron.

The formula for a compound made from fluorine and hydrogen is HF, because both fluorine and hydrogen are capable of forming only one covalent bond.

Therefore, the correct option is option B.

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Explanation:

d

hdjdjdjdjejdjjeuwuwuw

Answer:

D

Explanation:

I have this test as well

Answer:

Oxygen, Selenium, Calcium, Barium.

Explanation:

for plato user :)

Answer:  Screen shot

Explanation:

Explanation:

To solve this problem, we simply use the periodic table of elements which groups elements based on their atomic numbers.

The atomic number of an element is the number of protons it contains. The protons are the positively charged particles within an atom.

Now;

Noble gases  belongs to group 18

Alkali earth metals belongs to group 2

Halogens belongs to group  17

Alkali metals belongs to group 1

Transition metals belongs to group 3-12

Answer:

[tex]\boxed {\boxed {\sf About \ 2.23 \ moles \ CH_4}}[/tex]

Explanation:

First, find the molar mass of CH₄

This compound is made of carbon (C) and hydrogen (H). Look on the Peirodic Table for the masses of both elements.

Now, count the number of moles in the compound. There is no subscript on C, indicating 1 mole. There is a subscript of 4 on H, indicating 4 moles. We must multiply the molar mass of hydrogen by 4.

Add the 2 masses.

Next, find the number of moles in 35.7 grams.

Use the molar mass of CH₄ as a ratio.

[tex]\frac{16.043 \ g \ CH_4}{1 \ mol \ CH_4}[/tex]

Since we want the units of grams CH₄ to cancel when we multiply, we must flip the ratio.

[tex]\frac{1 \ mol \ CH_4}{16.043 \ g \ CH_4}[/tex]

Multiply by 35.7 grams.

[tex]35.7 \ g \ CH_4 *\frac{1 \ mol \ CH_4}{16.043 \ g \ CH_4}[/tex]

The grams of CH₄ will cancel each other out.  Since there is a 1 in the numerator, we can also move 35.7 to the numerator.

[tex]35.7 *\frac{1 \ mol \ CH_4}{16.043 }[/tex]

[tex]\frac{35.7 \ mol \ CH_4}{16.043}[/tex]

[tex]2.22526959 \ mol \ CH_4[/tex]

The original measurement given, 35.7 grams, has 3 significant figures (3, 5, and 7), so we must round to 3 sig figs.

For this number, it is the hundredth place.

The 5 in the thousandth place tells us to round the 2 to a 3.

[tex]2.23 \ mol \ CH_4[/tex]

There are about 2.23 moles of CH₄ in 35.7 grams.

Answer:

mass

Explanation:

Answer:

net force. sjiejsnssjwjehw

Answer:

net force or result force

Explanation:

mark brainliest please

♥answer♥

Physical

♥explanation♥

Physical changes alter only the size, shape, form or matter state of a material. Water boiling, melting ice, tearing paper, freezing water and crushing a can are all examples of physical changes.

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Answer:

Explanation:

Scientists know that there are 6x1023 molecules in a mole - so we have about 0.5x1023 molecules in our marble…and since every silicon dioxide molecule has one atom of silicon and two of oxygen, we have a grand total of 1.5x1023 atoms. That's 150,000,000,000,000,000,000,000 atoms

Answer:

Temperatures decrease with increasing height as the ozone layer is left behind and the air thins out with increasing altitude. The lowest portion of the low-pressure mesosphere is heated by the warm air of the upper stratosphere. This heat radiates upward, getting less intense as altitude increases.

Explanation:

Brainliest please?

Answer:

valence electrons

Explanation:

valence electrons

Answer:

PE = 73.58 J

Explanation:

Given data:

Mass of apple = 5 Kg

Height of tree = 1.5 m

Potential energy = ?

Solution:

Formula:

PE = mgh

g = 9.81 m/s

by putting values,

PE = 5 Kg × 9.81 m/s × 1.5 m

PE = 73.58 J (Kgm²/s = J)

Answer:

K₃PO₄ + 3HCl ⇒ 3KCl + H₃PO₄

Explanation:

practice these, it gets easier. goal is to match the amount of reactants and products on both sides of the equation. cheers!

Answer: rotation

Explanation:

orbitttttttttttt

Explanation:

Answer:

[tex]1S_{8} +12O_{2}=8SO_{3}[/tex]

[tex]2Al+6HCl=2AlCl_{3} +3H_{2}[/tex]

[tex]2Fe+3Cl_{2}=2FeCl_{3}[/tex]

[tex]2K+1Cl_{2}=2KCl[/tex]

Explanation:

Answer:

I believe the answer is a. I hope this helps

Answer: Mechanical energy usually means the sum of the kinetic energy and potential energy. So when you ride your bike you hope that the muscular (chemical) energy is converted mainly into mechanical energy.

Explanation:

Answer:

Isn't it neither.

Explanation:Because potential is going up and kinetic is going down.

Answer:

Specific heat, ratio of the quantity of heat required to raise the temperature of a body one degree to that required to raise the temperature of an equal mass of water one degree.

Explanation:

by dividing the heat capacity by the quantity of substance in a body, the resulting specific heat capacity is a function of the structure of the substance itself. In particular, it depends on the number of degrees of freedom that are available to the particles in the substance, each of which type of freedom allows substance particles to store thermal energy.

A radioactive decay is occurring by the emission of charged particles such alpha or beta to form a new stable atom with changes mass number and atomic number.

Heavy unstable radioactive elements undergo nuclear decay by which they form a stable isotope or new atom with changed atomic number. There are two types of nuclear decays mainly. They are alpha decay and beta decay.

During alpha decay isotopes with higher mass number undergo alpha emission and forming a new species with mass number reduced by 4 units and atomic number reduced by 2 units.

In the case of beta- decay, electrons are emitted from the atom and then forming a new atom with atomic number increased by one unit. For an electron capture process, an electron is captured to the atom forming an element with atomic number reduced by one.

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Answer:

can you like number them please? it would make it a lot easier

Explanation:

Answer: The box is moving downward with increasing speed.

Explanation:

The diagram models the forces acting on a box. 2N 2N- Box - 2 N 5 N .The box is moving downward with increasing speed best describes the motion of the box.

The normal force acting on the box is equal to and opposite to its weight. This term equals the force of gravity when the box is on a level surface. To calculate the normal force of the box, use our given mass and gravity's acceleration.

When an object interacts with another object, it experiences a push or pull that causes it to change state, either from rest to uniform motion. It is a magnitude and direction vector quantity.

A representation of the forces acting on the object. The object is represented by a dot, and forces are represented by arrows pointing away from the dot. Force diagrams are another name for them.

Thus, The box is moving downward with increasing speed best describes the motion of the box.

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Answer:

80000 grams

Explanation:

kilo  means 1000

80 x 1000 = 80, 000