Imagine that Ana has a block made of pure gold. If she cuts this block into two equal pieces, pick the statement that best describes the resulting pieces.

Answer:the advantage is that he discover many element unknown that time

And the disadvantage is wrong order of atomic masses and the position of isotopes

Explanation:

Answer:

Disadvantage: the isotopes and no separate position also as they have different atomic mass but same atomic number. Since the change in atomic mass of two successive elements was not constant therefore it was difficult to predict the number of missing elements with the help of atomic number only.

It could predict the existence of other elements and could predict their properties so, as to leave space in the periodic table. It could accommodate all the sixty elements discovered at that time and could accommodate the noble gases which, where discovered later.

Answer:

The correct option is;

Scientist propose explanations that can be explained by examining evidence

Explanation:

A scientists makes an hypotheses based on possible natural processes to explain the origin and/or the nature of the characteristics of a natural observation. The scientist then source more data and information to put their hypotheses to test. Due to the fact that an hypotheses is based on observable  processes and/or mechanisms, the given hypotheses can be further tested by other scientists through the use of their individually sourced data. From the result of the assessment, the hypotheses can be either accepted or rejected to enable the better clarification of the hypotheses when accepted or the development of a new hypotheses when rejected.

Answer:

The metric system is a system of measurement that uses the meter, liter, and gram as base units of length (distance), capacity (volume), and weight (mass) respectively.

Answer:

The metric system of units are:

a) meter

b) litre

c) gram.

Explanation:

These are all system of measurements.

okay.

Answer:

1.27 atm.

Explanation:

The following data were obtained from the question:

Pressure (P) in torr = 968 torr

Pressure (P) in atm =...?

Thus, we can convert from torr to atm by doing the following:

Recall:

760 torr = 1 atm

Therefore,

968 torr = 968/760 = 1.27 atm

Therefore, 968 torr is equivalent to 1.27 atm.

Answer: option d

Explanation:

Because every thing in our home is made from chemicals

Answer:

Cork the test tube and then heat it gently near the bottom only.

Explanation:

If the contents of the test tube is flammable, then it can catch fire easily at any time. In that case, we can not heat the mixture in an open test tube, that will make the flammable substance to catch fire easily.

In heating such a flammable material, the test tube should be securely corked and heat is delivered gently to the bottom of the tube. This will prevent the substance from bursting into flames spontaneously.

Answer:

The standard entalpy change for the reaction is 720 kJ/mol

Explanation:

The chemical equation for the reaction is given as follows;

TiO₂ (s) + 2C → Ti (s)  + 2CO

The standard enthalpy changes of formation for TiO₂ (s) = -940 kJ/mol

The standard enthalpy changes of formation for CO (g) = -110 kJ/mol

The enthalpy change of the reaction = The enthalpy of the products - The enthalpy of the reactants

Given that there are two moles of CO, we have;

The enthalpy of the products= -110 × 2 = -220 kJ/mol

∴ The enthalpy change = -220 - (-940) = 720 kJ/mol

The standard entalpy change for the reaction = 720 kJ/mol.

Explanation:

Make an observation

ask a question

form a hyposisese

make a prediction

test the prediction

use the results to fix the prediction and hypotheses

Answer:

1. Proton = 4

2. Neutron = 5

3. Electron = 2

Explanation:

9 4Be^2+

From the above, we obtained the following:

Atomic number = 4

Mass number = 9

Charge = +2

1. Determination of the proton.

Atomic number is simply defined as the proton number. This implies that:

Atomic number = proton number

Atomic number = 4

Therefore,

4 = proton number

Proton = 4

2. Determination of the Neutron.

Mass number = Proton + Neutron

Mass number = 9

Proton = 4

Neutron =?

Mass number = Proton + Neutron

9 = 4 + Neutron

Collect like terms

Neutron = 9 – 4

Neutron = 5

3. Determination of the electron.

From the question given

9 4Be^2+

The atom has a charge of +2. This implies that the atom has lose 2 electrons. Thus we can obtain the electron as follow:

Proton = 4

Charge = +2

Electron =?

Electron = Proton – charge

Electron = 4 – 2

Electron = 2

Answer:

alkaline earth metal

it's because calcium in the periodic table is located in group 2

Answer:

As scientist discovered that Science is the method of learning everything about the natural world.

An important role in science is to ask questions to get much more know to the topic.

Science is important to the natural world.

Science is the systematic study of the natural world through observation, experimentation, and analysis, aiming to understand its underlying principles and laws.

Science is the systematic and empirical study of the natural world and its phenomena through observation, experimentation, and the formulation of testable hypotheses. It aims to uncover the underlying principles and laws that govern the universe and provides a methodical approach to understanding, explaining, and predicting various aspects of the world around us. Science covers a wide range of disciplines, from physics and chemistry to biology, psychology, and beyond, and it plays a crucial role in advancing knowledge, technology, and society.

Science is important because it drives progress, expands knowledge, and improves lives by providing evidence-based solutions to complex problems. It fosters innovation, informs decision-making, and enhances our understanding of the universe and ourselves.

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Answer:

After three hours, concentration of C₂F₄ is 0.00208M

Explanation:

As the units of the rate constant of the reaction are M⁻¹s⁻¹ we can know this reaction is of second order. Its integrated law 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.

3.00 hours are in seconds:

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

Computing in the equation:

[tex]\frac{1}{[A]} =\frac{1}{[0.105mol / 4L]} +0.0410M^{-1}s^{-1}*10800s\\\frac{1}{[A]} = 480.9M^{-1}\\\[/tex]

[A] = 0.00208M

Answer:  Volume =  0.01L

Explanation:

The density of a substance is given by; Density =  Mass / Volume.

In this question, Mass = 1000g, Volume = ? and Density = 100 Kg/L

For the units to be uniform, we convert 1000g to Kg = 1Kg

Therefore, Volume = Mass / Density =  1Kg / 100Kg/L = 0.01L

Answer:

Rectifier

Explanation:

when The reading on a multi meter set used to test a diode shows a reading of approximately 0.6 Volt, it simply means that the diode being tested is a either a silicon diode or a rectifier.

setting the multi meter set to " Diode check" is done when one wants to check for the voltage ( forward or reverse bias ) across the diode. the current  passed through the diode is between : 1-10mA. and a reading of 0.6 to 0.7 volts indicates that the diode is a rectifier or a silicon diode

Answer:

It's just asking you to rearrange to equations to get what you want, so no numbers involved it's just teaching you the basics.

Explanation:

Explanation:

Hey, there!!

Given,

distance (s)= 120km

Time (t) = 1.5 hrs.

speed = ?

We have,

[tex]speed = \frac{s}{t} [/tex]

[tex]speed = \frac{120}{1.5} [/tex]

Therefore, the answer is 80km/hr.

Hope it helps...

Answer:

82.6 km/hr

Explanation:

hoped that helped

Answer:

20%of nitrogen in potassium nitrate

Answer:

0 to n − 1

Explanation:

The angular or orbital quantum number, gives a description of the particular subshell or orbital where the electron is found and gives the magnitude of its orbital angular momentum.

The values of the angular momentum quantum number (ℓ) takes on integer values that ranges from 0 to n − 1

Answer:

I think is B) All of these

Explanation:

Hey, there!!

The answer us option D.

Because acids easily reacts with metalic hydroxides to form salt and water.

[tex]hcl(aq) + naoh(aq) \: = h2o \: + \: nacl[/tex]

For option A, B and C.

SO, THE ANSWER IS OPTION D.

Hope it helps

-----------sucrose----------------

Water is a polar molecule that has the ability to dissolve the polar molecules. Sucrose being a polar molecule will be able to get dissolved. Thus, option b is correct.

Polarity is a characteristic shown by the polar molecules that shows covalent bonds and have electronegativity differences between the positive and the negative charges.

It has been said that a substance has a tendency to attract a similar substance and hence polar molecule of water attracts the sucrose molecule and easily dissolves it.

On the other side, limonene, oil, and atmospheric oxygen are non-polar molecules and hence are incapable of getting dissolved in another polar molecule.

Therefore, option b. sucrose gets dissolved in water.

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Answer:

0.1 grams per millilitre

Explanation:

Explanation:

Density = Mass/Volume = 10 g/100 mL = 0.1 grams per millilitre.

0.1 grams per millilitre, The density is 10 kg/mL

The density of a material can be defined as its mass per unit volume means it is the ratio between mass and volume, where the how much stuff an object has in a unit volume.

Density is a measurement of matter, where it shows how tightly matter is crammed together, it was discovered by the Greek scientist Archimedes

To calculate the density of an object, the mass (m) can be divided by the volume (v)

Density = Mass/Volume

The SI unit of density is kilogram per cubic meter (kg/m3) or in cgs unit of grams per cubic centimeter (g/cm3).

For example, Wood floats in water as it has lower density while anchor sinks because it has a higher density, similarly Helium balloons float because the density of the helium is lower than the density of air.

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Answer:

Making observation

Explanation:

Answer:

Yes they are safer.

Explanation:

As far as I know Spirit filled thermometers contain alcohol which is much less toxic than mercury.  Mercury is a heavy metal and is therefore fairly toxic similarly to lead.

I hope this helps let me know if anything is unclear.  

Your question has been heard loud and clear.

Yes , spirit filled thermometers are safer than mercury ones , actually they are made to be safer than the mercury.

In a spirit filled thermometer , it is precise and also there really is no risk of the stuff (usually alcohol or organic liquid) exploding if the thermometer glass breaks unlike the mercury thermometer , where if the glass breaks , there is a high risk of the mercury ball intoxicating the air and endangering lives.

Thank you

Answer:

1134

Explanation:

(the ones place was rounded up). 1133.981 is the unrounded answer.

Answer:

9

Explanation:

The structure of fluorophore used in the experiments has been drawn in the attachment. And from the drawing counting we can say that there are 9 sp2-hybridized carbon atoms present. Fiuorophores are a fluorescent chemical compound that can re-emit light upon light excitation. Normally used to produce absorbance and emission spectra.

Answer:

4.05 × 10²² atoms

Explanation:

Step 1: Given data

Mass of nickel: 3.95 g

Step 2: Calculate the moles corresponding to 3.95 g of nickel

The molar mass of nickel is 58.69 g/mol.

3.95 g × (1 mol/58.69 g) = 0.0673 mol

Step 3: Calculate the atoms in 0.0673 moles of nickel

We will use Avogadro's number: there are 6.02 × 10²³ atoms of nickel in 1 mole of atoms of nickel.

0.0673 mol × (6.02 × 10²³ atoms/1 mol) = 4.05 × 10²² atoms

Answer:

The amount of heat that must be added to raise the temperature of 1.90 mol of air from 18.0 ° C to 37.0 ° C at constant volume is 749. 9775 J

Explanation:

The properties cv and cp are called specific heats (or heat capacities) because, under certain special conditions, they relate the change in temperature of a system to the amount of energy added by heat transfer. Its SI units are [tex]\frac{J}{kg K}[/tex] or [tex]\frac{J}{mol K}[/tex]. Two specific heats are defined for gases, one for constant volume (cv) and the other for constant pressure (cp).

In the case of constant volume heating, the amount of heat entering the gas is equal to

Q=Cv*n*(Tfinal - Tinitial)

In this case:

Replacing:

[tex]Q=\frac{5}{2} *8.31 \frac{J}{mol K} *1.90 mol* (37 - 18)[/tex]

Taking into account that the difference in degrees kelvin is equal to the difference in degrees Celsius, and solving you get:

[tex]Q=\frac{5}{2} *8.31 \frac{J}{mol K} *1.90 mol* 19 K[/tex]

Q= 749. 9775 J

The amount of heat that must be added to raise the temperature of 1.90 mol of air from 18.0 ° C to 37.0 ° C at constant volume is 749. 9775 J