what is the mass number? plz help!

Answer:

The first 3

Explanation:

Eukaryotic cells are usually multicellular, contain a true nucleus, and contain membrane-bound organelles. Hence, options A, B and C are correct.

The eukaryotic cell has a nuclear membrane that surrounds the nucleus, in which the well-defined chromosomes (bodies containing the hereditary material) are located.

Eukaryotic cells are usually multicellular, contain a true nucleus, and contain membrane-bound organelles.

Hence, options A, B and C are correct.

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Answer to Question.

A physical change is a change to the physical—as opposed to chemical—properties of a substance. They are usually reversible. The physical properties of a substance include such characteristics as shape (volume and size), color, texture, flexibility, density, and mass.

Answer:

A prefix

Explanation:

you're welcome

The covalent molecules named as,

So, option B is correct one.

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Answer:

An atom's electronegativity is affected by both its atomic number and the distance at which its valence electrons reside from the charged nucleus. The higher the associated electronegativity, the more an atom or a substituent group attracts electrons.

Explanation:

Hope this helps :)

Answer:

either a car or a rock

Explanation:

because the rock can weigh more than the car , and vice-versa with the car weighing more than the rock

Answer:

5.9e-5

Explanation:

Answer:

An element is a single atom by itself found on the periodic table. A compound  is made when two or more elements chemically bond together. An example of an element is hydrogen. (H) An example of a compound is [tex]H_{2} O[/tex].

Explanation:

explained above

Answer:

D

Explanation:

Move the decimal and count the places

Answer:

0.497 moles/L

Explanation:

The reaction that takes place is:

First we calculate the moles of lactic acid in 0,821 g, using its molar mass:

One mole of lactic acid reacts with one mole of sodium hydroxide (it is a monoprotic acid), so in 18,34 mL of NaOH solution there are  9,122x10⁻³moles of NaOH:

Answer:

4.75 or 4.8

Explanation:

density = mass / volume

57 / 12 = 4.75

from here you can leave it as is or round up.

hope this helps!!

Answer:

[tex]\boxed {\tt Number \ and \ unit}[/tex]

Explanation:

The two requirements for a measurement are a number and a unit.

For example, here is a measurement:

38.6 cm

The number is 38.6 and the unit is cm, or centimeters.

Therefore, both number and unit are correct.

Answer:

288 grams

Explanation:

The amount of any radiative substance left after some time is calculated by

amount left = [tex]x/2^n[/tex]

where x is the initial amount of substance

n is the number of half lives

one half live is the time in which amount of substance reduce to half of its initial value.

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amount left = 4.5 grams

half life of  iodine-125 = 60 days

total time in which substance reduced to 4.5 grams  = 360 days

thus,

number of half life in 60 days = 360/60 = 6

thus, there are period of 6 half lives

in each half life the amount of substance reduces to its previous half

let the initial amount be x grams

using the formula

amount left = [tex]x/2^n[/tex]

[tex]4.5 = x/2^6 \\ 4.5 = x/64\\x = 4.5*64 = 288[/tex]

Thus, 288 grams was the initial amount of iodine-125

Answer:Mole, also spelled mol, in chemistry, a standard scientific unit for measuring large quantities of very small entities such as atoms, molecules, or other specified particles.

Explanation:

Answer:

V = 3.75 cm³

Explanation:

Density = Mass / Volume

Step 1: Define variables

D = 8.00 g/cm³

M = 30.0 g

V = unknown

Step 2: Substitute and Evaluate for V

8.00 g/cm³ = 30 g/ V

V = 15/4 cm³

V = 3.75 cm³

Answer:

it doesnt even give you enough information for you to answer it

Explanation:

Answer:

it doesnt even give you enough information for you to answer it

Explanation:

Answer:

7.11 x [tex]10^{14}[/tex] Hz

Explanation:

The equation for converting wavelength to frequency is ν=c/λ, or the speed of light over wavelength. The speed of light is 3.00 x [tex]10^{8}[/tex], and our wavelength here is 422 x [tex]10^{-9}[/tex]. All we have to do now is substitute our given values:

[tex]\frac{3.00x10^{8} }{422x10^{-9}}[/tex]

After reduction, our answer comes out to be about 7.11 x [tex]10^{14}[/tex] Hz.

The greenhouse effect is a process in which gases in the atmosphere keep heat near earth and prevent it from radiating into space.

Greenhouse effect can be described as the process by which radiations from the sun are absorbed by greenhouse gases and do not travel back into space. This prevents the surface of the earth from freezing.

The sun heats up the earth’s atmosphere during the day and the earth cools down at night by radiating heat back into the atmosphere. The heat is absorbed by the greenhouse gases and makes the surface of the earth warmer, which makes the survival of living beings on earth possible.

But because of the increased levels of greenhouse gases, the temperature of the earth has considerably increased. The major contributors to greenhouse gases are automobiles, deforestation,  factories, etc. which increases the amount of these gases in the atmosphere.

The greenhouse gases do not allow radiation or heat to escape from the earth and increasing the surface temperature of the earth and leading to global warming.

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Answer:  Chemical symbols are used to represent atoms and elements.  A compound consists of atoms of two or more elements combined in a small, whole-number ratio. Atoms of each of its elements are always present in the same ratio

Explanation:

When paper is burned, the mass of the remaining ash is less than the mass of the original paper because Some of the products of the reaction were given off as a gas.

The postulate of the law of conservation of mass is that mass can not be created or destroyed rather it can be transformed from one form to another.

This means that when ash is left behind after burning paper, the total mass should be the same as was obtained before combustion but it rather weighs less than paper itself. This should never be interpreted to mean that mass was "lost".

Here is what happens, paper is an organic material and burning it in air yields CO2 gas which escapes into the atmosphere. This explains why; when paper is burned, the mass of the remaining ash is less than the mass of the original paper.

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Answer:

730 mL which is .73 L

Explanation:

Answer:

Several heavy elements, such as uranium, thorium, and plutonium, undergo both spontaneous fission, a form of radioactive decay and induced fission, a form of nuclear reaction.

Answer:

B. They move freely in all directions.

Explanation:

i got it right on my test on edge

Answer:

B. They move freely in all directions.

Explanation:

Answer:

D. Luster

Explanation:

Luster describes how a mineral reflects off light. It is in the definition.

Mass spectrometry is the technique that measures the ratio of mass to charge. The spectrum of the element Sb is most likely represented by 121 and 123 atomic mass. Thus, option B is correct.

Mass spectrometry plots the spectrum representing the ratio of mass-to-charge by the signals generated by the ions. The spectrum estimates the mass and isotopes of the sample elements. They also determine the chemical properties and structures.

The spectrometry detects the isotopes that are stable and are known to have the same atomic number. It can be used to determine the isotopes of an element based on their peaks generated on the mass spectrum. Antimony has two stable isotopes with atomic masses 121 and 123.

Therefore, option B. the spectrum of the element Sb is most likely represented by Sb-121 and Sb-123.

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12 Km / hour

Explanation:

using the formula

average speed =  ( where time is in hours )

40 min =  =  hour

speed = 8 ÷  = 8 ×  = 12 Km / hour

Answer:

12 Km / hour