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3 years ago

Which best describes accuracy?

Chemistry

2 answers:

jekas [21]3 years ago

8 0

I would go with b: the reproducible of a measured value. but im not 100%

GalinKa [24]3 years ago

3 0

Answer:

the agreement between a measured value and an accepted value

Explanation:

Accuracy measures how close a measured value is to a standard value. For example, if the weight of a bag of rice is 1 kg and the measured value is 0.90 kg rather than 0.75 kg, then the former measure value is more accurate than the later measured value.

Precision on the other hand is how close are the measured values to one another. For example, if that same 1 kg rice bag was measured 3 times and the readings were 0.75 kg, 0.73 kg and 0.74 kg then the measured values are precise but inaccurate.

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What is an atomic reaction

castortr0y [4]

Atomic reaction is nothing but the reaction of one atom with the other atom to form the new compound.

<u>Explanation:</u>

The atom is considered as the ultimate basic particle of the matter.
This atom comprise of electron neutrons and protons.
Generally in the atomic reaction, there will be loss or gain of the electron to or from the substance with which the reaction takes place.

In default, all atoms wanted to attain the noble gas configuration which is stable in nature. These atoms from the ionic or covalent bond by sharing the electron.

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8 0

3 years ago

How many grams of methane gas occupy a volume of 11.2 liters at stp

Anni [7]

Answer:

see the pic for the answer

4 0

3 years ago

Antacids work to relieve stomach acids because of which of the following types of reactions?

Anastaziya [24]

<u>Answer:</u> The correct answer is Option B.

<u>Explanation:</u>

Decomposition is a type of chemical reaction in which larger compound breaks down into two or more smaller compounds.

$AB\rightarrow A+B$

Double displacement reactions is defined as the chemical reaction in which exchange of ions takes place.

$AB+CD\rightarrow AD+CB$

Synthesis reaction is a type of reaction in which two or more smaller compounds combines to form a single large compound.

$A+B\rightarrow AB$

Single displacement reaction is a type of reaction in which a more reactive metal displaces a less reactive metal from its chemical reaction.

$A+BC\rightarrow AC+B$

In stomach, an acid is present known as hydrochloric acid and to neutralize its effect, antacid is taken which has $CaCO_$ as a component.

The reaction between HCl and $CaCO_3$ is a type of neutralization reaction and it is a type of double displacement reaction.

The equation between the two follows:

$CaCO_3+HCl\rightarrow CaCl_2+H_2O+CO_2$

Hence, the correct answer is Option B.

4 0

3 years ago

If a substance has a half life of 58 years and starts with 500 g radioactive, how much remains radioactive after 30 years?

Vilka [71]

Answer:

A = 349 g.

Explanation:

Hello there!

In this case, since the radioactive decay kinetic model is based on the first-order kinetics whose integrated rate law is:

$A=Ao*exp(-kt)$

We can firstly calculate the rate constant given the half-life as shown below:

$k=\frac{ln(2)}{t_{1/2}} =\frac{ln(2)}{58year}=0.012year^{-1}$

Therefore, we can next plug in the rate constant, elapsed time and initial mass of the radioactive to obtain:

$A=500g*exp(-0.012year^{-1} *30year)\\\\A=349g$

Regards!

5 0

3 years ago

Draw the alkene formed when 1-heptyne is treated with hbr in the presence of peroxide.

Nimfa-mama [501]

<h2>Heptene formed is -</h2><h2> $CH_3-CH_2-CH_2-CH_2-CH_2-CH=CHBr$ </h2>

Explanation:

The two possibilities when the peroxide is not present

$CH_{3}-CH_{2}-CH_{2}-CH_{2}-CH_{2}-C$ ≡ $CH +HBr$ → $CH_3-CH_2-CH_2-CH_2-CH_2-CBr=CH_{2}$

$CH_3-CH_2-CH_2-CH_2-CH_2-CBr=CH_2$ + HBr → $CH_3-CH_2-CH_2-CH_2-CH_2-CBr_2-CH_3$

In presence peroxide,

$CH_3-CH_2-CH_2-CH_2-CH_2-C$ ≡ $CH$ + HBr → $CH_3-CH_2-CH_2-CH_2-CH_2-CH=CHBr$

When peroxides are present in the reaction mixture, hydrogen bromide adds to the triple bond of heptane with regioselectivity.

This reaction is opposite to that of Markovnikov's rule which says that when asymmetrical alkene reacts with a protic acid HX, then the hydrogen of an acid is attached to the carbon with more in number of hydrogen substituents, and the halide (X) group is attached to the carbon with more in number of substituents of alkyl.
One mole of HBr adds to one mole of 1-heptane.
The structure of heptene formed is -

$CH_3-CH_2-CH_2-CH_2-CH_2-CH=CHBr$

5 0

3 years ago