The atomic masses in the Periodic Table are not integral numbers. For example, carbon is listed as 12.011 amu instead of 12.000 amu. Why?

Answers

Answer 1

Answer: The reason that the atomic masses shown on the periodic table include fractions, is to account for the other isotopes of the element, not just the pure element. Remember, an isotope is a atom of an element with a reduced or increased number of neutrons. This changes the atomic mass but not the charge. The number is calculated by multiplying the atomic mass of each isotope of the element with its percent abundance found in nature. Therefore it is an averaged atomic mass for all of the element. For example, carbon-12 may (I don't know the real numbers) have a % abundance of 98.5%, and carbon-14 may have a percent abundance of 1.5%, so that is why carbon would have an atomic mass greater than 12.000.

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Samarium-146 has a half-life of 103.5 million years. After 1.035 billion years, how much samarium-146 will remain from a 205-g sample?0.200 g
0.400 g
20.5 g
103 g

Answers

Answer : The correct option is, 0.200 g

Solution :

As we know that the radioactive decays follow first order kinetics.

First we have to calculate the rate constant of a samarium-146.

Formula used :

$t_(1/2)=(0.693)/(k)$

Putting value of $t_(1/2)$ in this formula, we get the rate constant.

$103.5* 10^6=(0.693)/(k)$

$k=6.6* 10^(-9)year^(-1)$

Now we have to calculate the original amount of samarium-146.

The expression for rate law for first order kinetics is given by :

$k=(2.303)/(t)\log(a)/(a-x)$

where,

k = rate constant = $6.6* 10^(-9)year^(-1)$

t = time taken for decay process = $1.035* 10^(9)years$

a = initial amount of the samarium-146 = 205 g

a - x = amount left after decay process = ?

Putting values in above equation, we get the value of initial amount of samarium-146.

$6.6* 10^(-9)=(2.303)/(1.035* 10^(9))\log(205)/(a-x)$

$a-x=0.200g$

Therefore, the amount left of the samarium-146 is, 0.200 g

Ans: 0.200 g

Given:

Half life of Sm-146 = t1/2 = 103.5 million years

Time period, t = 1.035 billion years = 1035 million years

Original mass of sample, [A]₀ = 205 g

To determine:

Amount of sample after t = 1035 million years

Explanation:

The rate of radio active decay is given as:

$A(t) = A(0)e^(-0.693t/t1/2) \n\n= 205 g * e^{(0.693*1035)/(103.5) } \n\n= 0.200 g$

Many chemical and toxic substances used in modern industry are flammable or combustible. true/false

Answers

Answer:

True

Explanation:

Many chemical and toxic substances used in modern industry are indeed flammable or combustible. These substances can pose significant safety hazards, especially in industrial settings, and require proper handling, storage, and safety measures to prevent fires and explosions. It is crucial to follow strict safety protocols and regulations when working with such materials to ensure the safety of workers and the environment.

The process of a material going through a change of state from a gas to a liquid is called

Answers

The process of a Material Going from a Gas to liquid is known as Condensation

this is condensation (like when steam turns to water on the sides of a hot drink)

Provide a balanced equation for the reaction between lead nitrate and sodium chloride

Answers

Answer:

Pb(NO3)2 + 2NaCl = PbCl2 + 2NaNO3

Explanation:

Lead nitrate is Pb(NO3)2

Sodium Chloride is NaCl

The basic reaction is:

Pb(NO3)2 + NaCl = PbCl2 + NaNO3

Now we need to balance the equation. Note that the lead nitrate contributes 2 (NO3) units, but there is only 1 NO3 on the product side. So start by adding a second NaNO3:

Pb(NO3)2 + NaCl = PbCl2 + 2NaNO3

Now we have 2 Na atoms on the right side, so add a "2" to the NaCl:

Pb(NO3)2 + 2NaCl = PbCl2 + 2NaNO3

This is starting to look good. Lets check the atom/unit counts on both sides of the equation:

Reactants Products

Pb 1 1

NO3 2 2

Na 2 2

Cl 2 2

The equation is now balanced. Pb(NO3)2 + 2NaCl = PbCl2 + 2NaNO3

The symbol for the metric unit used to measure mass is?

Answers

Answer: Kilograms (kg)

Explanation:

Answer:

(g)

Explanation:

(g) is the symbol of a gram which is the metric unit that measures mass.

Hope that helps!

which atomic particle determines the chemical behavior of an atom the nucleus, neutron, electron, proton or none of these

Answers

The chemical behavior of an atoms is determine by the formation or destruction of chemical bonds. The chemical bonds are the result of the interaction of the electrons of the atoms. Chemical properties of the atoms are given by how attached are the shell electrons attached to the nucleus and how they interact with other atoms. Chemical changes are the result of exchange valence electrons of the atoms. So, the answer is the atomic particle that determines the chemical behavior of an atom is the electron, because it is the particle that is active in chemical bonding.

The electron is the primary atomic particle that determines an atom's chemical behaviour.

Electrons are negatively charged particles that form electron shells or energy levels around an atom's nucleus. They are engaged in the production and breaking of chemical bonds, hence they play an important part in chemical reactions.

The quantity and configuration of electrons in an atom's outermost energy level (valence electrons) are very significant in determining the chemical characteristics of the atom. Because of the identical number of valence electrons, elements in the same group or column of the periodic table frequently show similar chemical behaviour.

To know more about electron, here:

brainly.com/question/12001116

#SPJ6

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