An isotope of cesium (cesium-137) has a half-life of 30 years. If 1.0 g of cesium-137 disintegrates over a period of 90 years, how many g of cesium-137 would remain?​

Answer:

CaC

O

3

--------> CaO + C

O

2

20.7 g 6.81g +

As per the law of Conservation of mass , in any chemical reaction, the total mass of products is equal to the total mass of the reactants.

mass of C

O

2

+ mass of CaO is equal to the mass of CaC

O

3

.

mass of C

O

2

+ 6.81g = 20.7g

mass of C

O

2

= 20.7g- 6.81g = 13.89g

% yield of a Product Z = mass of product Z x 100 / mass of reactant

% yield of Product C

O

2

= 13.89 x 100 / 20.7 = 67. 10%

% yield of Product CaO = 6.81g x 100 /20.7 = 32.89%

Explanation:

:)

Answer:

3 x 10^26

Explanation:

You take the number of moles (500) and multiply it by Avogadro's number (6.022 x 10^23) to get the answer.

The number of molecules in one mole of Cl₂ gas is 6.022× 10²³ . Then 500 moles of Cl₂ is 3.01 × 10²⁶.  

Any substance containing 6.022× 10²³ number of atms is called one mole of the substance. This number is called the Avogadro number. Thus, one mole of  every elements contains Avogadro number of atoms.

Similarly,  one mole of any compounds contains Avogadro number of molecules. One mole of Cl₂ contains 6.022× 10²³ Cl₂ molecules. Thus, the number of molecules in 500 moles of chlorine gas is calculated as follows:

Number of molecules of chlorine gas =  500 ×  6.022× 10²³ = 3.01 × 10²⁶.

Therefore, there will be 3.01 × 10²⁶ number of molecules in 500 moles of chlorine gas.

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Answer:

Hey

Explanation:

The normal range for urine specific gravity is 1.005 to 1.030.

Answer:

Option B. Single replacement reaction

Explanation:

To know which option is correct, it is important that we know the definition of each option. The definition of each option is given below:

1. Synthesis reaction is a reaction in which two different elements or compound combine together to produce a new compound different from the two starting elements or compound. An example is illustrated below:

C + D —> E

2. Single replacement reaction is a reaction in which an element replaces or displaces another element in a compound. An example is illustrated below:

D + BC —> B + CD

3. Combustion reaction is a reaction in a substance react with oxygen to generate carbon dioxide (CO₂) and water (H₂O). An example can be seen when organic compound react with oxygen to produce carbon dioxide (CO₂) and water (H₂O). This is illustrated below:

CₓHᵧ + (x + y/4) O₂ —> xCO₂ + (y/2) H₂O

4. Double replacement reaction is a reaction in which the ions of the two reacting compound replaces one another to form new products. This is illustrated below:

X⁺Y¯ + U⁺V¯ —> X⁺V¯ + U⁺Y¯

5. Decomposition reaction is a reaction in which a large compound breaks down into two or more elements or compound. An example is illustrated below:

GH —> G + H

Now, observing the equation given in the question above:

Sn + 2HCl —> SnCl₂ + H₂

We can see that Sn replaces H in HCl to produce SnCl₂.

Therefore, the reaction is a single replacement reaction.

Answer:

¹/3 C3H8(g) + ⁵/3 O2(g)

Explanation:

The coefficient before every molecule is representative of the number of moles. We can represent it in ration form so as to calculate the question;

C₃H₈(g) + 5 O₂(g) → 3 CO₂(g) + 4 H₂O(l) means;

For every 1 mole of C₃H₈(g) and 5 moles of  O₂(g) produces  3 moles of  CO₂(g) and 4 moles of H₂O(l).

Therefore to produce 1.00 mole of CO₂(g);

We represent it in ratio;

C₃H₈(g) : CO₂(g)

1  :     3

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We can write:

5/4 = 3,8/x

Solving for x:

x = 3,04 mols of H2O

Calculating the H2O mass:

M H2O = 18 g/mol

n = m/M

Solving for m:

m = 54,72 g of water

****************************

Using the same, but with molar mass:

M CO2 = 44 g/mol => 3 x 44 = 132 g

M O2 = 32 g/mol => 5 x 32 = 160 g

160/132 = x/90,6

solving for x:

x = 109,82 g if CO2

Answer:

true

Explanation:

Answer:

gravity

Explanation:

gravity

Answer: Vibråtory movement.

Explanation: when particles bounce against each other the friction creates thermal energy. Think about what happens when you rub your hands together and they get warmer, that the friction between your hands making thermal energy.

Answer:

C = 18.29 g  

Explanation:

Given data:

Mass of beryllium needed = ?

Mass of nitrogen = 18.9 g

Solution:

Chemical equation:

3Be + N₂    →    Be₃N₂

now we will calculate the number of moles of nitrogen:

Number of moles = mass/molar mass

Number of moles = 18.9 g/ 28 g/mol

Number of moles = 0.675 mol

Now we will compare the moles of nitrogen and Be from balance chemical equation.

                     N₂        :       Be        

                       1          :       3

                  0.675       :      3/1×0.675 = 2.03 mol

Number of moles of Be needed are 2.03 mol.

Mass of Beryllium:

Mass = number of moles × molar mass

Mass = 2.03 mol ×   9.01 g/mol

Mass = 18.29 g  

Answer:

K₂CrO₅

Explanation:

The empirical formula is the simplest formula of a compound. To find the empirical formula, we follow the procedure below:

Elements                         Potassium                 Chromium         Oxygen

Mass                                  6.52                             4.34                  5.34

Molar mass                          39                               60                      16

Number of moles             6.52/39                     4.34/60             5.34/16

                                             0.167                          0.072              0.333

Divide through by

the smallest                      0.167/0.072             0.072/0.072          0.333/0.072

                                            2.3                               1                                4.6

                                             2                                 1                                  5

Empirical formula K₂CrO₅

Heat required = 220 cal

Given

2 g ice at -20°C into water at 20°C

c ice =  0.5 cal g-1 °C-1

Lf = 80 cal/g

Required

Heat

Solution

The heat needed to raise the temperature

Q = m . c . Δt

1. heat to raise temperature from -20 °C to 0 °C

Q = 2 x 0.5 x 20

Q = 20 cal

2. phase change(ice to water)

Q = m.Lf

Q = 2 . 80 cal/g

Q = 160 cal

3. heat to raise temperature from 0 °C to 20 °C ( c water = 1 cal/g.C)

Q = 2 . 1 . 20

Q = 40 cal

Total heat = 220 cal

Answer:

1.50 moles of POH or Potassium Hydroxide.

Explanation:

First of all, find the substance formula

The substance formula of Potassium Hydroxide is

KOH

Second of all, if you want to convert from grams to moles, you use molar mass of KOH

Third of all, find the molar mass of KOH.

K = 39.1 amu

O = 16.0 amu

H= 1.0 amu

Potassium has 1 atom, oxygen has 1 atom, and hydrogen has 1 atom.

So do this:

39.1(1) + 16.0(1) + 1.0(1) = 56.1

The molar mass of KOH is 56.1 g/mol.

Fourth of all, use dimensional analysis to show your work.

84.20 grams of KOH * 1 mol/56.1 g/mol

The moles will cancel out.

84.20 divided by 56.1 = 1.500892166

But I have to round my answer to two digits after the decimal points instead of using sig figs.

So I round to the hundredths place

1.500892166 = 1.50

So the final answer is 1.50 moles(don't forget the units) of POH.

Hope it helped!

Answer:

Within each element square, information on the element's symbol, atomic number, atomic mass, electronegativity, electron configuration, and valence numbers can be found. At the bottom of the periodic table is a two row block of elements that contain the lanthanoids and actinides.

Explanation:

Answer:

Na2O (the 2 is small the o is not a 0 but and OOh)

Explanation:

Hey there, The formula for the compound formed between sodium and oxygen will be Na2O

Though since sodium is a metal and oxygen is a nonmetal, Na2O is expected to be ionic.

An ionic compound is a chemical compound made up of ions held together by electrostatic forces known as ionic bonding.

To determine an ionic compound's formula, first identify the cation and record its symbol and charge.

After that, identify the anion and record its symbol and charge. Finally, mix the two ions together to make an electrically neutral compound.

After two or more atoms lose or gain electrons to form an ion, an ionic bond can form.

Ionic bonds form when metals lose electrons and nonmetals gain electrons. Ions with opposite charges attract each other, forming an ionic bond.

The symbol for sodium is Na+, and the symbol for oxygen is O2. The resulting compound here in the given condition is Na2O.

Thus, this is the formula for the ionic compound formed between sodium and oxygen.

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Answer:

the first hill of the roller coaster

Explanation:

The first hill of a roller coaster is always the highest point of the roller coaster because friction and drag immediately begin robbing the car of energy. At the top of the first hill, a car's energy is almost entirely gravitational potential energy (because its velocity is zero or almost zero).

Answer:

top of the hill

Explanation:

Answer:

1–ethoxybutane

Explanation:

In naming the above compound, the following must be observed:

1. The longest chain gives the root name of the compound.

2. The shorter chain is named as substituent together with the oxygen group as alkoxy.

3. Locate the position of the alkoxy group by giving it the lowest low count.

4. Combine the above to obtain the name of the compound.

Now we shall name the compound as follow:

1. The longest chain is carbon 4 i.e butane.

2. The shortest chain is ethyl (i.e –CH₂CH₃). This is named together with the oxygen atom as ethoxy.

3. The ethoxy group is located at carbon 1 of the butane chain since it is the functional group of the chain.

4. The name of the compound is:

1–ethoxybutane.

Answer:

4.935×10-1

Explanation:

Take away the 0

Answer:

fewest; the same significant figures with; measured numbers.

Explanation:

Without mincing words let us dive straight into the solution to the above question. In order to be able to use the significant figures properly one must know the rules attached to it uses. This is so, because they contributes to the precision of measurements.

When performing multiplication or division calculation, the number of significant figures in the answer[result] will be determined by the one with the smallest number of significant figure in the problem. Therefore, if we have 6.56 which is three[3] significant figures and 1.2 which is two[2] significant figures, then the number of significant figures will be two[2].

6.56 × 1.2= 7.872 = 7.9[ to 2 significant figures].

Answer:

Okay so I have no idea what the options are but a chemical change is when you modify the substance itself.

LIKE....

burning paper

metal rusting

fireworks going off

Answer:

The waves travel in a direction parallel to direction of the vibration of the medium

The waves travel in a direction parallel to direction of the vibration of the medium

A mechanical wave is defined as an oscillation of matter which is responsible for energy transfer via  medium.

The propagation of  wave is limited by the medium of transmission, the oscillating material which revolve around a fixed point with little translational motion.

A surface wave which is an example of  mechanical wave that propagate  along the interface of two different media in physics. other common examples are Gravity waves on the surface of liquids, ocean waves.

Surface wave can be propagated in a slow way through Earth material and are generally lower in frequency than body waves.

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Answer:

0.0064 qt

Explanation:

Given data:

Density of mercury = 13.6 g/cm³

Mass of mercury = 83.0 g

How many quarts mercury have = ?

Solution:

First of all we will calculate the volume in cm³.

d = m/v

13.6 g/cm³ = 83.0 g / volume

Volume = 83.0 g /  13.6 g/cm³

Volume = 6.1 cm³

cm³ to L:

6.1 cm³ × 1 L / 1000  cm³

0.0061 L

In quarts:

1 L = 1.06 qt

0.0061 L × 1.06 qt / 1 L

0.0064 qt

Answer:

Explanation: An isolated system is a system in which matter and energy both can not transfer through its boundry

Answer:its going to be a

Explanation:

Answer:

it will option A bcs motion increases when temp increases

Answer:

K and Mg

Explanation: This is because: Discussion of calcium is often paired with magnesium, and for good reason. As neighbors on the periodic table, they have similar chemical properties and behave similarly in several chemical reactions. They share some regulatory mechanisms and act in many of the same physiologic arenas.

Answer:

Explanation:

HCl    + NaOH     =    NaCl    +     H₂O.

1 mole   1 mole           1 mole          1 mole

6.93  g of hydrochloric acid = 6.93 / 36.5 = .189 mole of HCl

2.4 g of NaOH = 2.4 / 40 =  .06 mole of NaOH

NaOH is in short supply so it is the limiting reagent .

1  mole of NaOH reacts with 1 mole of HCl to give 1 mole of Water

.06 mole of NaOH will react with .06 mole of HCl to give .06 mole of water

Water formed = .06 mole

= .06 x 18 = 1.08 g

= 1.1 g

Answer:

3

Explanation:

The reaction expression is given as:

      Al(OH)₃  +   HNO₃   →    H₂O   +  Al(NO₃)₃  

To solve this problem, let us assign coefficient a,b,c and d to each specie;

           aAl(OH)₃  +   bHNO₃   →    cH₂O   +  dAl(NO₃)₃  

Conserving Al : a  = d

                   O:  3a + 3b  = c + 9d

                   H: 3a + b  = 2c

                   N: b  = 3d

let a = 1 , d  = 1, b  = 3 , c = 3

  Multiply through by 3;

 a  = 1, b  = 3, c = 3 and d  = 1

   Al(OH)₃  +   3HNO₃   →    3H₂O   +  Al(NO₃)₃