Write an experiment ?

Answer:

There are 17.64% students received B+ grades.

Explanation:

It is given that,

Total number of students in chemistry class is 17

We need to find the percentage received by B+.

Number of students having B+ grades are 3 (from graph)

Required percentage = [tex]P=\dfrac{3}{17}\times 100=17.64\%[/tex]

So, there are 17.64% students received B+ grades.

Explanation:

The Absorption of Light by Chlorine, Bromine and their Gaseous Mixtures

Answer:

in a laboratory

Explanation:

A controlled experiment refers to the one where everything is an experiment except a single variable is held constant. A collection of information is typically taken as a control group, which is generally the ordinary state, and another group is analyzed( such as chemical reaction as per the question) in which all conditions are similar to the control group except for the variable under examination. The main benefit of a controlled experiment is that confusion over the accuracy of the results can be eliminated more easily.

Answer:

i think quantitative observation

Explanation:

First find the mass of 1 mole of water (Molecular mass)

[tex] H_{2} O = 2H + O [/tex]

[tex]

= 2(1) + 32 [/tex]

[tex]

= 34 \: grams

[/tex]

Hence 1 mole of water is 34 g

Compare

1 mole = 34 g

1.33 mole = x g

[tex] \frac{x}{34} = \frac{1.33}{1} [/tex]

[tex]

x = 1.33 \times 34 [/tex]

[tex]

\color{blue}{\boxed{x = 45.2}} \: \: \: \: to \: 3 \: s.f.

[/tex]

Therefore 1.33 moles of water is 45.2 grams

The mass of the substances can be given by the molar mass and the moles of the substances. The mass of 1.33 mole of water is expressed in grams as, 23.94 grams.

The mass has been defined as the product of the moles of the substance and the molar mass in grams per mole. The mass is given in grams and has a formula,

Moles = mass ÷ molar mass

Mass = molar mass × moles

Given,

Moles = 1.33 moles

Molar mass of water (H₂O) is calculated as = 2 (1) + 16= 18 grams per mole

Using the formula of mole, mass is calculated as:

Mass = molar mass × moles

mass = 1.33 × 18

= 23.94 grams

The mass of the substance can be calculated if the value of the molar mass and the moles of the substance has been known. The molar mass of the substance can be calculated by adding the mass of the individual masses of the element in a molecule.

Therefore, 1.33 mol of water contains 23.94 grams.

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Answer:

2 protons, 1 electron, 7 neutrons, and 3 electrons

Explanation:

Make a He atom with a mass of 4. How many protons did you put in the nucleus?

2 protons

Make a Li atom with a mass number of 7. How many electrons did you place in the outermost orbital  (ring)?

1 electron

Make a N atom with a mass number of 14. How many neutrons are in the nucleus?

7 neutrons

Make a B atom with a mass number of 11. How many electrons did you put in the second orbital (ring)?

3 electrons

Answer:

2 protons, 1 electron, 7 neutrons, and 3 electrons

Explanation:

Answer:

c

Multiply 3,000 by 3.8 and divide the result obtained by 12

Answer:

Hope it helps you dude :)

Answer:

Mass of CO2 WILL BE ~ 9.33 g

Explanation:

Moles of O2 = 14/18

Let the mass of CO2 be x

Then moles of CO2 will be = x/12

moles of CO2 = moles of O2

x/12 = 14/16

x = 9.33 grams

Answer:

first conclusion was that the whole world is made up of only 4 elements but as the time passed more elements were discovered... if the world would not contain more elements... you wouldn't be alive.

• Before the balloon was placed inside the hot water, the pressure was the same inside and outside the balloon. The hot water raised the kinetic energy of the air molecules inside the balloon, expanding the balloon, through thermal expansion.

• (1) the pressure of air inside the balloon increased, (2) the volume of the inside of the balloon increased as well, and (3) the temperature of the balloon increased. Note that pressure and volume are inversely proportional, and pressure and temperature are directly proportional. Therefore as the temperature increases, the pressure inside will increase, causing an increase in the volume. At a certain point though the volume will increase too much as to cause a significant decrease in pressure.

• The air molecules will gain kinetic energy, hence (1) increasing the molecules's speed, and (2) heating the air molecules.

Answer:

Yes

Explanation:

Some environmental factors- chemical, physical (UV), and biological (poisonous plants)- have the capability to damage DNA. This can lead to mutation, cell death, and several ailments.

Chemicals such as pesticides and heavy metals can be found in the environment (air, water) or in some consumer products.

The presence of Lead and a reactive oxygen species can result in DNA damage. Arsenic is classified as a carcinogen (cancer-causing substance).

More details are found in scientific articles online, but here's a helpful snippet- "heavy metal exposure can contribute to genetic damage by inducing double strand breaks (DSBs) as well as inhibiting critical proteins from different DNA repair pathways"

Lead and arsenic are heavy metals that are considered carcinogens. These metals cause alteration and damage to the genetic material and protein synthesis.

Carcinogens are said to be a substance that can lead to cancer in an organism and are produced naturally from viruses and ultraviolet rays or mna made by cigarette smoking and chemicals.

Their high exposure causes the breaking of the double strand of the DNA molecule in the cells that inhibits and prevents protein formation leading to interference with the DNA repair pathways.

Cadmium, lead, arsenic, etc., are heavy metals that are released by human activities and alter the genetic mechanism and composition leading to mutation and disorders like skin cancers, lung cancer, etc.

Therefore, lead and arsenic is carcinogens that damage DNA.

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Explanation:

ATOMIC THEORY

Lesson 1 - Page 5

J.J. Thomson

In 1897, English physicist J. J. Thomson (1856–1940) disproved Dalton’s idea that atoms are indivisible. When elements were excited by an electrical current, atoms break down into two parts. One of those parts is a negative tiny particle, which Thomson called a corpuscle in 1881. The term electron was introduced in 1891 by G. Johnstone Stoney (1826-1911) as a way to describe a “natural unit of electricity.” Thomson envisioned these negative charges embedded into positive charges, like an English plum pudding. The plums were the electrons and the pudding was the positive matter.

Thomson's idea of an atom did not survive very long. English physicist Ernest Rutherford (1871–1937) studied the effects of bombarding thin gold foil with alpha particles. Alpha particles are helium atoms that have lost their electrons and are positive. Rutherford’s model had a nucleus, which occupied a very small area toward the middle, and was positive. He used the term proton for the positive particles. However, his electrons were moving on the outside of the nucleus in no definable manner in his model.

A is Dalton's Model; B is Thomson;

and C is Ruthford's model of an atom

Answer:

Fractional column is an essential item used in distillation of liquid mixtures so as to seperate the mixture into its component parts, or fractions based on the differences in volatilities.

Explanation:

Answer:

Explanation:

An atom is composed of a nucleus and electrons orbiting around it,and the nucleus itself contains protons and neutrons (with the exception of protium, an isotope of hydrogen with only a proton in the nucleus) because each element contains a specific and unique number of protons, but the number of neutrons can vary,an element, therefore, can have several variants, called isotopes, which differ slightly in the composition of the nucleus,the number of electrons can also change in an atom, giving us positive or negative ions.

=Br-79 has 79 nucleons. 79 protons and neutrons. We know that bromine has 35 protons, and 35 electrons, so all we need to do is subtract. 79 nucleons - 35 protons = 44 neutrons,

Subtract the atomic number from the mass number,the result gives you the number of neutrons in the isotope,look to see if the isotope has a charge, denoted by a superscript number and a plus or minus sign next to it,subtract the charge from the atomic number if the charge is positive,the result is the number of electrons in the isotope,add the absolute value of the charge to the atomic number if the charge is negative,the result is the number of electrons in the isotope.

= 35 from 79 and you will get 44. 44 is the number of neutrons in the Br-79 isotope.

79-Br+, that means:

It’s still a Br (bromine) atom, so it doesn’t change the number of protons //because changing the number of protons, it won’t be bromine anymore//

So bromine atom has 35 protons

So, isotope means many forms of atoms with the same element, which are different from atomic mass (or more clearly, the number of neutrons) → 79 (this number is shown for the atomic mass) - 35 = 44 neutrons

It has 35 protons, 34 electrons and 44 neutrons. The way to figure this out is - the protons of an element never change. So when you say bromine, you look it up on the Periodic table and you see its atomic number (aka # of protons) is 35. It will always be 35 for bromine. Then you take the charge into account. In this case, the charge is +1. Since protons can’t change, electrons must. One more proton equals one less electron. So 34 electrons. The atomic weight of a number (79 in this case) is = # of protons + # of neutrons. So neutrons = 79 - 35 = 44.

Hope this helps!

Answer:

After three hours, concentration of C₂F₄ is 0.00208M

Explanation:

The rate constant of the reaction:

2 C2F4 → C4F8 is 0.0410M⁻¹s⁻¹

As the units are M⁻¹s⁻¹, this reaction is of second order. The integrated law of a second-order reaction is:

[tex]\frac{1}{[A]} =\frac{1}{[A]_0} +Kt[/tex]

Where [A] and [A]₀ represents initial and final concentrations of the reactant (C₂F₄), K is rate constant (0.0410M⁻¹s⁻¹) and t is time of the reaction (In seconds).

3.00 hours are in seconds:

3 hours ₓ (3600 seconds / 1 hour) = 10800 seconds

Initial concentration of C2F4 is:

0.105mol / 4.00L = 0.02625M

Replacing in the integrated law:

[tex]\frac{1}{[A]_0}= \frac{1}{0.02625} +0.0410M^{-1}s^{-1}*10800s\\\frac{1}{[A]_0}=480.9M^{-1}[/tex]

[A] = 0.00208M

Answer:

A=0.173 Km

B=0.00256 km

C=56.7 m

D=5130 mm

Explanation:

first we need to know that

[tex]1km=1000m\\\\1dm=0.1m\\\\1000mm=1m[/tex]

so we can form the following

[tex]\frac{1km}{1000m}=1\\\\\frac{0.1m}{1dm} \\\\\frac{1000mm}{1m}[/tex]

so in A

[tex]17.3m\\\\=17.3m*1\\\\=17.3m(\frac{1km}{1000m} )\\\\=0.0173km[/tex]

in B

[tex]2.56m\\\\=2.56m*1\\\\=2.56m(\frac{1km}{1000m} )\\\\=0.00256km[/tex]

in C

[tex]567dm\\\\=567dm*1\\\\=567dm(\frac{0.1m}{1dm} )\\\\=56.7m[/tex]

in D

[tex]5.13m\\\\=5.13m*1\\\\=5.13m(\frac{1000mm}{1m} )\\\\=5130mm[/tex]

Answer:

Ionic bond is the intermediate in strength.

Explanation:

Ionic bond is weaker than covalent bond and stronger than hydrogen bond in strength because in ionic bond, the atoms attract each other due to opposite in charge. Ionic bond is a type of bond in which one atom losses electron completely and become cation (positive charge) while the other atom receive the electron and become anion (negative charge). so they attract each other due to opposite charges.

Answer:

it us false

Explanation:

air and gas don`t have definite shape

but solid have all definite

Answer:

Alchemy is a practice of making gold from other metals.

Explanation:

Alchemy is a method which is practiced by the ancient scientists of Europe, Africa and Asia trying to produced gold from other metals. This method was failed to produced gold from metals and all scientist suggested that metals can not be converted into gold. Greeks were the people who presented the theory of alchemy in the first few centuries of CE.

Answer:

the answer is Alchemy was scientific because it included observations and experiments

Explanation:

i took the test

Answer:

ch4 + 2o2 gives co2+2h2o +891kj

Explanation:

becoz 891kj heat energy is given out

exothermic process means heat energy is given out/ released

Among the given reactions the exothermic reaction is option a. The reaction between methane and oxygen giving out carbon dioxide and water with 891 KJ of heat energy.

An exothermic reaction is the reaction in which heat is evolved from the reaction system to the surroundings. The reaction container will be too hot to touch.

The enthalpy change for an exothermic reaction is negative. Whereas that for an endothermic reaction is positive where, heat is absorbed into the reaction system.

For the given reactions, all other reactions except option a are intaking some heat energy that's why written in the left side of arrow which are endothermic. Option a is the combustion of methane gas and it is exothermic.

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Answer:

Ksp= 7.98 × 10^-13

Explanation:

According to the question, we are to calculate the solubility constant (Ksp) of Zinc carbonate (ZnCO3) in a dissolved solution.

The equilibrium of the reaction is:

ZnCO3 (aq) ⇌ Zn2+ (aq) + CO32- (aq)

According to this; 1 mole of Zinc carbonate (ZnCO3) dissolves to give 1 mole of Zinc ion (Zn2+) and 1 mole of carbonate ion (CO32-).

This illustrates that:

(Zn2+) = 1.12 x 10-4 g/L

(CO32-) = 1.12 x 10-4 g/L

However, 1.12 x 10-4 g/L is the solubility in mass concentration of ZnCO3, we need to convert it to molar concentration in mol/L by dividing by the relative molar mass of ZnCO3.

To calculate the molar mass of ZnCO3, we say:

Zn (65.4) + C (12) + 03 (16×3)

= 65.4+12+48

= 125.4g/mol.

Hence, molar concentration= 1.12 x 10-4 g/L / 125.4 g/mol

= 8.93 × 10^-7 mol/L.

Therefore;

Zn2+) = 8.93 x 10-7 mol/L

(CO32-) = 8.93 x 10-7 mol/L

Ksp = [Zn2+] [CO32-]

Ksp = (8.93 x 10-7) × (8.93 x 10-7)

Ksp = 7.98 × 10^-13

Answer:

The comparison of the damages generated by Hurricane Donna with respect to others. The empirical information that can support this may be the number of homes affected or the cost of repairs after the hurricane has passed until it stops.

Explanation:

Empirical knowledge is the knowledge that it generates from experience and observation, perception tells us how something works and its natural characteristics.

If a scientist assures that it was the most severe hurricane, it is because the scientist is comparing the disasters generated by Hurricane Donna with other ones.

Answer:

I'm not quite sure.....

Explanation:

Answer:

Hey there!

Density=Mass/Volume

Density=1.2/4555

Density=2.63e-4g/cm^3

Let me know if this helps :)

Answer:

1.  Chloro(methylchloranuidyl)methane

2.   1-Chloro-3,3-dimethylbutane

3.  2-bromobutane

Answer:

Explanation:

You can do this by doing dimensional analysis.

The first step is to change grams to mg

1000 mg = 1 gram

So the fraction will look like this

1.03 g * 1000 mg/ 1 gram = 1030 mg (the grams cancel out)

Now move onto the volume. The volume is actually 1 cm^3. This becomes 1 cm^3 / 1000 mm^3

So the answer becomes

1030 mg / cm^3 * ( 1 cm^3/1000 mm^3) The cm^3 cancel out

1030 mg / 1000 mm^3

1.030 mg/ mm^3

Answer:

I'm pretty sure is a mixture

Answ  Es la B .

Explanation

By raising the temperature of a liquid, it turns into a gas, therefore its particles will have more movement and its kinetic energy will increase. the more you raise the temperature, the more space they will have between the molecules.

Answer:

yes, this is an acceptable practice in research.

Explanation:

Note that, having a different result in one's research does not imply it is automatically invalid. However, because there may have been some errors or limitations in the previous work by the male researcher, it is possible that the later results are more accurate, even though she used the same procedures. She may have been more careful when calculating her results.

Answer:

Since the results did not match, she should repeat the investigation again. If the data still cannot be replicated, then the results are not valid. In that case, the next step is to restart the process of inquiry from the beginning. An improved design might produce valid, repeatable results.

Explanation: