The half-life of cobalt-69 is 6 years. How much of a 5-gram sample is left after 12 years

Answer:

I am expecting that is option is d is correct answer

Explanation:

because in the grassland some animals can live

Answer:

all of them

Explanation:

took test

Floods can cause soil erosion and sedimentation. It will destroy all the properties of human beings. All the options are correct. Thus the correct option is D.

Flood is defined as a natural disaster which results from the overflow of water on land. It is mainly generated by the heavy rainfall, sudden snow melt, etc. It affect the ecosystem adversely.

The floods are mostly affected to the coastal regions. It is even a threat to life of people. The habitat of aquatic organisms are destructed by the floods. The ground water is found to be contaminated with pathogenic microbes and causes water borne diseases.

As a result of floods the life of small insects which play a primary role in the ecosystem of food chain is also affected. All fields like education, communication, transport, etc. of our state is affected by the floods.

The floods can cause loss of people, low water quality, destruction of habitats. Some times the effect of flood in our life will be long lasting.

Thus the correct option is D.

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Answer:

53.7kPa

Explanation:

Given parameters:

Total pressure of the mixture  = 96.4kPa

partial pressure of hydrogen  = 13.4kPa

partial pressure of oxygen  = 29.3kPa

Unknown:

partial pressure of methane  = ?

Solution:

The total pressure of mixture is equal to the sum of their particles pressures;

   Partial pressure of methane  = 96.4kPa - (13.4kPa + 29.3kPa)

  Partial pressure of methane = 53.7kPa

Answer: 53.6

Explanation: I just took the test and got it right.

Answer:

D as a mixture is not a compound and it does not have it's own chemical formula

Explanation: Sauce me brainliest

It cannot be described by a chemical symbol or formula.

- Chilio

Answer:

A book on a shelf

Explanation:

Answer:

The plasmodial slime molds are the kind of protist that can live in groups in which different individuals perform different jobs. Some kinds of bacterial cell walls also have other functions.

Answer:

In neutral atom number of electrons (negativity charged particle) and number of proton ( positively charged particle) are equal.

When one or more electrons are lost so positive charge particle increases and cation is formed.

For example in Na 11 electrons and 11 protons are present when it loses one electrons protons are 11 and 10 electron are remaining so one positive charge is present.

Morever when an element gain electrons one negative charge increases and anion is formed. For example in Cl 17 proton and 17 electrons are present when it gain one electron 18 electrons and 17 protons are now present one negative is more so anion negative ion is formed.

Explanation:

Answer:

30.6 L

Explanation:

Given data:

Number of molecules of nitrogen = 8.23×10²³ molecules

Volume occupy at STP = ?

Solution:

Standard temperature = 273.15 K

Standard pressure = 1 atm

One mole of any substance at STP occupy 22.4 L volume.

Number of moles of nitrogen:

1 mole contain 6.022×10²³ molecules.

8.23×10²³ molecules × 1mol / 6.022×10²³ molecules

1.37 mol

Volume of nitrogen:

1.37 mol × 22.4 L / 1 mol

30.6 L

Answer:

SYMBOLS, FORMULAS AND MOLAR MASSES

OBJECTIVES

1. To correctly write and interpret chemical formulas

2. To calculate molecular weights from chemical formulas

3. To calculate moles from grams using chemical formulas

INTRODUCTION

Part I. Symbols and formulas

An element is a homogeneous pure substance made up of identical atoms. All matter is made

up of elements and, since chemistry is the study of matter, it is convenient to use symbols to represent

the elements rather than using the entire name.

By international agreement, specific symbols are assigned to each element (Note: This means

that while names of the elements vary with language, symbols are constant throughout the world.) Each

element is assigned a one- or two-letter symbol. The first letter is capitalized, the second (if there is

one) is not. While this often seems trivial, it is in fact a very important point. For example, in chemical

language Co represents cobalt, which is a metal and an element, while CO represents carbon monoxide,

a compound which is a colorless, odorless gas! Even when there is not an obvious correspondence,

for instance "MN", it can cause confusion. Do you mean the element manganese? Did you forget a

letter and mean something else? Are you using "M" to represent something else entirely? Chemists

sometimes use "M" to represent any metal. It is well worth the trouble to memorize the symbols for

common elements.

Since compounds consist of elements, the chemical formulas of compounds also consist of

elements with subscripts used to denote the number of atoms per molecule. If there is no subscript, it is

implied that there is one of that kind of atom. Ones never appear in chemical formulas. Not only do

subscripts denote ratios of atoms, they also denote the ratio of moles of element to one mole of

compound. Parentheses can be used to show groups of atoms, with the subscripts showing how many

groups there are. Parentheses are not used if there is only one group.

Examples: For one mole of the following compounds, how many moles of each element are

present?

MgCl2 1 mole Mg, 2 moles Cl

Mg(NO3)2 1 mole Mg, 2 moles N, 6 moles O

NaNO3 1 mole Na, 1 mole N, 3 mole O

AgCl 1 mole Ag, 1 mole ClPart II. Molar Masses

Each atom has a different size and therefore a different mass. The relative masses of each

element can be found on the periodic table. For example, one atom of magnesium weighs 24.31 amu

(atomic mass units). However, one mole of magnesium weighs 24.31 g. (Moles were planned that

way!) Since one mole of MgCl2 consists of one mole of magnesium and two moles of chlorine, the

mass of one mole of MgCl2 must be the sum of the masses of the elements. The mass of one mole of a

substance is called the molar mass or molecular weight.

Examples: What is the molar mass of the following compounds?

MgCl2 24.31 + 2(35.45) = 95.21 g/mol

Mg(NO3)2 24.31 + 2(14.01) + 6(16.00) = 148.33 g/mol

NaNO3 23.00 + 14.01 + 3(16.00) = 85.01 g/mol

AgCl 107.9 + 35.45 = 143.4 g/mol

(Note: Yes! You DO have to count significant figures when calculating molecular weight/molar

mass. However, the number of significant figures may vary depending on which periodic table you use.)

Chemists are generally interested in number of moles. Unfortunately, it is impossible to measure

moles directly. However, masses are easily measured, and if the chemical formula of the compound is

known, the molar mass can be used to determine the number of moles. The molar mass is defined as:

molar mass = grams/moles = g/mol (1)

Moles may be calculated by using molar mass as a conversion factor in dimensional analysis where

molar mass in grams = 1 (exactly) mole of compound (2)

This method is used in multi-step calculations. For example, if 0.873 g of MgCl2 is weighed out, it

is 9.17 x 10-3

moles.

1 mole

0.873g x 95.21 g = 9.17 x 10-3

mol MgCl2 (3)

However, 0.873 g of AgCl is only 6.09 x 10-3

mol.

1 mole

0.873g x 143.4 g = 6.09 x 10-3

mol AgCl (4)Molar mass may also be used to relate moles to grams. For example, 0.158 mol of MgCl2 is 15.2 g.

0.158 mol x 95.21 g = 15.2 g MgCl2 (5)

1 mol

Percent is used to express parts per one hundred. Usually in chemistry, it refers to

g of species of interest x 100 = % (6)

g of whole thing

Example: For the % Mg in MgCl2: In one mole of MgCl2, there are 24.31 g of Mg (molar mass of Mg,

the part we are interested in) and 95.21 g of MgCl2 (the whole thing), so %Mg in MgCl2 is

(24.31/95.21) x 100 = 25.53% Mg (7)

PROCEDURE

Work individually.

The formula for calcium phosphate is Ca3(PO4)2. Weigh about 2 g of calcium phosphate to the

nearest 0.001 g. In other words, you do not have to have exactly 2.000g, but you must know the

weight you have exactly. Acceptable results include but are not limited to: 1.985g , 2.035g, 2.314g

etc.

Be sure to report all results with the correct number of significant figures and appropriate units!

Answer:

The correct answer is c. Your welcome

[tex]\tt =3000~L\times \dfrac{289}{312}\times \dfrac{99}{45.5}[/tex]

Given

3000 L of gas at 39°C and 99 kPa to 45.5 kPa and 16°C,

Required

the new volume

Solution

Combined with Boyle's law and Gay Lussac's law  

[tex]\tt \dfrac{P_1.V_1}{T_1}=\dfrac{P_2.V_2}{T_2}[/tex]

T₁ = 39 + 273 = 312

T₂ = 16 + 273 = 289

Input the value :

V₂ = (P₁V₁.T₂)/(P₂.T₁)

V₂ = (99 x 3000 x 289)/(45.5 x 312)

or we can write it as:

V₂ = 3000 L x (289/312) x (99/45.5)

Answer:

Argon is a chemical element with the symbol Ar and atomic number 18.

Explanation:

Answer:

Avogadro's number is a very important relationshiptoremember: 1 mole = 6.022×1023 6.022 × 1023atoms, molecules, protons, etc.

...

Explanation:

jayfeather friend me

Answer  C) 6 × 1023 atom

The number of silver atoms present in one mole of silver is 6.0 × 10²³ atoms. The correct option is C) 6 × 1023 atoms

From the question, we are to determine the number of silver atoms present in one mole of silver.

From the formula,

Number of atoms = Number of moles × Avogadro's constant

Number of atoms = 1 × 6.022 × 10²³

Number of atoms = 6.022 × 10²³

Number of atoms ≅ 6.0 × 10²³ atoms

Hence, the number of silver atoms present in one mole of silver is 6.0 × 10²³ atoms. The correct option is C) 6 × 1023 atoms

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Answer:

protons(positively charged) and the neutrons (no charge)

Explanation:

Answer:

The nucleus of an atom contains protons and neutrons.

Answer:

Intensive

Explanation:

Aluminium is an Intensive Metal

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The pressure of the gas = 40 atm

Given

200 ml container

P = 2 atm

final volume = 10 ml

Required

Final pressure

Solution

Boyle's Law  

At a fixed temperature, the gas volume is inversely proportional to the pressure applied  

[tex]\tt \rm p_1V_1=p_2.V_2\\\\\dfrac{p_1}{p_2}=\dfrac{V_2}{V_1}[/tex]

Input the value :

P₂ = P₁V₁/V₂

P₂ = 2 x 200 / 10

P₂ = 40 atm

10 ml should the patient take in each dose

Given

125 mg of penicillan ⇒ 4 times/day

The concentration = 250 mg/5 ml

Required

The volume of the dose

Solution

The mass of penicillan/day :

= 125 mg x 4 times

= 500 mg

The volume/day :

= 500 mg : 250 mg/5 ml

= 10 ml

Answer:

In the first generation, the beetles changed to have light spots. The beetles with the light spotted trait had a better chance of survival causing the species evolved to have lighter spots.

Answer:

In the first generation, the beetles with the dark spotted trait had a better chance of survival. The trait mutated over time, causing the beetles with that trait to be darker.

Explanation:

In the picture that I had, it shows that some of the beetles in the first generation started to develop spots on their back or wings. It shows that later down the line, their backs start to get even more darker which means that is must be a trait that mutated over time that would allow the beetles with that trait to be significantly darker. They can't just change their traits if they want to so it would have to be something like mutation that caused it.

As the amount of salt in water increases, the density of the water increases. The more particles present in unit volume the more densely packed the substance.

Density of a substance is the measure of its mass per unit volume. Density describes how closely its particles are  packed. Densely packing means more particles in a unit volume.

The density of water is 1 g/ml. However, when the salinity increases, the salt solution increases in density by the solute particles. If the density of an object is less than water, it will float on it. Objects denser than water will sink on water.

As the salinity increases, density of water increases, makes the surface tension also increases, which best illustrates what happens in dead sea. Hence, option b is correct.

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Answer: Why don't we feel the air pressing on us all the time?

Explanation:

Because air is a fluid, the weight of the air is transmitted to the palm of your hand and to the back of your hand at the same time. These forces cancel so that your hand overall feels no net force

Answer:the gravity in the atmosphere is pulling all the air so we can survive

Explanation:

A. A poster that features brief sentences conveys urgency and simplifies content.

Answer:

Se Puede Traducir?

Explanation:

Mmm?

Answer:

i think it is surroundings