what are isotopes and explain why​

Answer:They can be spread through skin contact, bodily fluids, airborne particles, contact with feces, and touching a surface touched by an infected person.

Immunise against infectious diseases.

Wash and dry your hands regularly and well.

Stay at home if you are sick.

Cover coughs and sneezes.

Clean surfaces regularly.

Ventilate your home.

Prepare food safely.

Practise safe sex.

Explanation:

Answer:

1. Dissolving powder in milk - Chemical

  - It is chemical because the milk has changed on a molecular level

2. Toasting bread - Chemical

   - It is chemical because adding heat to the bread cooks it, therefore

     changing it on a molecular level

3. Melting cheese - Physical

   - It is physical because the physical appearance was the only change

4. Slicing apples or bannanas - Physical

   - It is physical because the physical appearance was the only change

5. Frying an egg - Chemical

   - It is chemical because new particles were formed

6. Milk souring - Chemical

   -  It is chemical because it is forming a new product (lactic acid)

Explanation:

Physical Change occurs when the particles of a substance become rearranged, but do not change into different particles.  

Chemical change occurs when a new substance is formed. This process is irreversable.

Answer:

give the preson above brainly bc there right

Explanation:

To measure the density of the stone placed in a graduated cylinder let us follow these steps bellow

We know that the formula for density is given as

Given data

Mass = 8gram

Initial Volume of water in cylinder = 25mL

Final Volume of water in cylinder  = 29mL

Hence the volume of the rock  = 29-25 = 4mL

Therefore the density of the rock = 8/4 = 2 g/mL

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Elements are arranged from left to right and top to bottom in order of increasing atomic number. Order generally coincides with increasing atomic mass. The rows are called periods.

Answer: C

Explanation: This is because of a nice thing called guessing

Answer:

phosphorus

Explanation:

mark me brainliest pl

Answer:

B, D, C

Explanation:

the solution may have more than one solute, a solution is a homogenous mixture of 2 or more substances and not all solutions are liquid

A solution is formed by the mixture of substances dissolved in water. There may have more than one solute. Not all solutions are liquid but there exists solid solutions too. Hence, options A, B, C are correct.

A solution is a combination of a solvent and a solid solute. The solute can be completely dissolved in the solvent and can have a partial solubility.

Water is a good solvent which dissolve majority of compounds. But there are other solvents too forming solution with suitable solutes. Solutions can be homogenous or heterogenous. Homogenous solutions are forming one phase and the solute particles are uniformly arranged.

Heterogeneous solutions are those where the solute particles are arranged in a non-uniformity and they form a different phase from the solvent.

There can be more than one solute in a solution provided that the solute can be of miscibility with each other.

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Answer:

Silicon Dioxide is a compound usually referred to as Quartz, it's a crystalline sort of material that is commonly found and used for equipment and furniture (like tables for example). Their molecular geometry is of tetrahedral shape (how their bonds look like and such)

Gold is an element that is a transitional metal that is quite malleable (able to hammer it to sheets) and is ductile (can be made into wires). As you probably have guessed, gold is used a lot for jewelry due to its lustrous appearance, and the fact that it can't corrode as well as its rarity. Due to it not being able to corrode, it's pretty useful in circuitry as it requires less management unlike elements with higher electrical conductivity like copper or silver. However gold is pretty costly so it's not often relied on for technology and mostly just used for show instead.

N2 or nitrogen gas, may seem like a compound for people new to chemistry but is actually just a diatomic molecule, meaning they are composed of only 2 atoms. So elements that are diatomic are commonly found with only 2 atoms (Oxygen gas for example, or Hydrogen gas) Nitrogen is part of the "magnificent seven" (the elements which are diatomic".  Nitrogen is essential for a lot of living things (aside from us), and since they are the most abundant material in our air (78% of air is Nitrogen), there's plenty of life growing.

Compound and elements are differ from each other. Silicon dioxide ( SiO₂ ) is compound , gold ( Au ) is  element and nitrogen gas ( N₂ ) is compound.

Elements are always made-up of only one type of atom. Molecule is made up of more than one type of atom. Silicon dioxide is a compound, which is crystalline in nature. Their molecular geometry is of tetrahedral shape.

Gold is an element that is a transitional metal that is quite malleable and is ductile.  Gold ( Au ) is used a lot for jewelry. Nitrogen gas is  compound . It is diatomic in nature, So elements that are diatomic are commonly found with only 2 atoms.

Hence, silicon dioxide is compound, gold is element, and nitrogen gas is also compound.

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Answer:

ok

Explanation:

Answer:

896.5

Explanation:

You want to manipulate each equation individually.

First Equation: Keep it how it is, because N2 is the same in the final and 1st equation

Second Equation: Multiply the enthalpy by 4 because you want the H2Os to be equal

Third Equation: Switch the sign of the enthalpy because you want toe H2O2 on the other side of the equation, and multiply by 2 to match the coefficient

Answer:

this might be of help to u

Not every earthquake has a(n) Foreshock, but every earthquake has an Aftershock that occurs in the Same place as the mainshock.

An earthquake is defined as a natural disaster in which there are tectonic plates that are present on the earth's crust collides with each other.

An Earthquake can be minor as well as natural depending upon the frequency it causes the damage. Earthquake is the Shaking of Earth and was much destruction of the economy and manpower.

Surroundings are being disturbed like trees will fall, and buildings will collapse which will cause damage to the economy as well as to human life.

Foreshock is the before shop which happens before the earthquake and aftershock is the other socks that happen after the earthquake

Thus, the correct options are 1. Foreshock, 2. Aftershock, 3. The Same place as.

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Answer:

Electrons are stored in different electron shells with the nucleus in the center. Depending on the size of the element, the electrons may need more shells, making the electrons further away from the nucleus.

Explanation:

Atoms contains nucleus in its center and electron that revolve around the atom in fixed orbit.  the statement "electrons are always located close to the nucleus of an atom" is not really accurate.

Atom is the smallest particle of any element, molecule or compound. Atom can not be further divided.

In the nucleus, proton and neutron are present. Electron has -1 charge while proton has +1 charge.

Electrons always move in fixed orbit around the nucleus with a particular force. Electrons may or may not be close to the nucleus. Depending on the size of the element, the electrons may need more shells, making the electrons further away from the nucleus.

Therefore,  the statement "electrons are always located close to the nucleus of an atom" is not really accurate.

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Answer:

The answer is C.  Because particles can never stop moving

Explanation:

"All matter has thermal energy, even matter that feels cold. That's because the particles of all matter are in constant motion and have kinetic energy."

Answer:

0.09375 M

Explanation:

You want to use the following equation:

M1*V1=M2*V2

Then plug in the 50ml to V1 and 0.15M to M1 and 80ml to V2 (add the 50 and 30). The next thing you want to do is change the mL to liters, since Molarity is moles/liter. Once that is done, solve algebraically for answer.

** Also don't forget to capitalize the M when you mean Molarity, because it is different than m.**

Hope this helps!

Answer:

that's a weird question

Explanation:

why do you need to know that?

Answer:

option C two organisms with desired traits are bred

Answer:

5 ms2

Explanation:

The acceleration of the ball is 5 ms2.

Acceleration is the rate at which an object's velocity with respect to time changes. It is a vector quantity to accelerate (in that they have magnitude and direction). The direction of the net force acting on an object determines the direction of its acceleration.

The acceleration of the car in its present direction of motion is referred to as a linear acceleration (or tangential acceleration in circular motions), and the passengers on board feel a force pressing them back into their seats as a result.

The acceleration that is used to change direction is referred to as radial acceleration (or centripetal acceleration in circular travels), and the reaction that the passengers feel is a centrifugal force.

Therefore, The acceleration of the ball is 5 ms2.

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Answer: Sodium also floats on the surface, but enough heat is given off to melt the sodium (sodium has a lower melting point than lithium and the reaction produces heat faster) and it melts almost at once to form a small silvery ball that dashes around the surface.

Explanation:

Answer:

hydroxide.

Explanation:

Alkali metals are in group 1 of the Periodic Table. They are on the left of the Periodic Table. These are the alkali metals as follows:

When alkali metals react with water they make alkaline solutions, so the universal indicator turns people and they produce hydrogen and a metal hydroxide. When sodium is put in water, the metal floats on the surface it reacts to form sodium hydroxide and hydrogen.

Answer: B. no

Explanation:

Considering the reaction stoichiometry, 0.00495 grams of water is produced when  2.75×10⁻⁴ moles of NaOH reacts completely.

Sodium hydroxide (NaOH) and hydrochloric acid (HCl) react to form sodium chloride (NaCl) and water. So, the balanced reaction is:

NaOH + HCl → NaCl + H₂O

By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:

In the periodic table, you can find the molar mass of the elements, also called atomic mass or atomic weight. So, to calculate the molar mass of a compound, you must add the molar mass of the elements of the compound multiplied by the times they appear in the compound.

So, in the case of water:

H₂O= 2× 1 g/mole + 16 g/mole

H₂O= 18 g/mole

Then, if by stoichiometry of the reaction 1 mole of water is produced, the mass of water produced is calculated as:

mass H₂O= 1 mole× 18 g/mole

mass H₂O= 18 g

Then you can apply the following rule of three: if by stoichiometry 1 moles of NaOH produce 18 grams of H₂O, 2.75×10⁻⁴ moles of NaOH will produce how much mass of H₂O?

[tex]mass of H_{2} O=\frac{2.75x10^{-4} moles of NaOHx18 grams of H_{2} O}{1 mole of NaOH}[/tex]

mass of H₂O= 0.00495 grams

In summary, 0.00495 grams of water is produced when  2.75×10⁻⁴ moles of NaOH reacts completely.

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Answer:

d

Explanation:

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

Answer:

D. vinegar

Explanation:

Hope this helps you!!

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Answer:Wood for barbucue.

Explanation:

It is recommended only for the second type of candy to be taken off the market.

Based on the background information, if a candy shows a 0,62 Rf value in the chromatography it is considered potentially dangerous, and therefore it should be taken off the market.

The Rf value is calculated using the following formula:

Now, let's find out if any of the components has an Rf equal to 0,62.

Note: To determine the distances I measured the image using a ruler and you can do the same, this will not alter the results.

     2. Sample 2

This means sample 2 has the 0.62 Rf value and therefore it needs to be taken off the market.

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Answer:

45th answer is pure and properties 42 is periodictable

Answer:

4. A gene is introduced into salmon to make them grow twice as fast.

Answer:

Asexually

Explanation:

Plant's cannot reproduce sexually