Answer:
5 significant figures
Explanation:
Answer:
69.3%
Explanation:
The question should read as follows:
A weak acid, HA, has a pKa of 4.357. If a solution of this acid has a pH of 4.005, what percentage of the acid is not ionized? Assume all H⁺ in the solution came from the ionization of HA.
The Henderson-Hasselbalch equation relates the pKa and pH of a solution to the ratio of ionized (A⁻) and unionized (HA) forms of a weak acid:
pH = pKa + log ([A⁻]/[HA])
Substituting and solving for [A⁻]/[HA]:
4.005 = 4.3574 = log([A⁻]/[HA])
-0.3524 = log([A⁻]/[HA])
[A⁻]/[HA] = 0.444/1
The percentage of acid that is not ionized (i.e. the percentage of acid in the HA form) is calculated:
[HA]/([A⁻] + [HA]) x 100% = 1/(1+0.444) x 100% = 69.3%
(2) increases
(3) remains the same
As the elements in Group 17 are considered in order of increasing atomic number, the chemical reactivity of each successive element decreases.
The impetus for a chemical substance to undergo a chemical reaction, either by itself or with other materials, with an ease and overall release of energy is referred to as reactivity.
Group 17 are the halogens group and on moving from top to bottom across that group atomic size of the atoms increases due to the increase in the number of energy shells. As a result of which it decreases the affect of nuclear attraction force to the outer most valence shell decreases.
Hence, reactivity decreases.
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Carbon
Quartz
Hematite
b. a beta particle
c. gamma radiation
d. all of the above
Answer: The radiation that is emitted from the above process is alpha particle.
Explanation:
Alpha decay is defined as the process in which alpha particle is emitted. In this process, a heavier nuclei decays into a lighter nuclei. The alpha particle released carries a charge of +2 units. The released alpha particle is also known as helium nucleus.
Beta decay is defined as the process in which beta particle is emitted. In this process, a neutron gets converted to a proton and an electron. The released beta particle is also known as electron.
Gamma decay is defined as the process in which an unstable nuclei gives off excess energy by a spontaneous electromagnetic process and thus releases .
These radiations does not carry any charge and are electrically neutral.
The chemical equation for the decay of polonium-212 isotope follows:
Hence, the radiation that is emitted from the above process is alpha particle.
Answer:
It should be used 2 digits to the right of the decimal point to report the result
Explanation:
When adding or subtracting two decimal numbers, the number of digits to the right of the decimal point in the result is equal to the amount with the least number of decimal places.
In this case we have 4 decimal places in 0.0136 g, 2 decimal places in 2.70 × 10-4 g and 2 decimal places in 4.21 × 10-3 g, so, the least number of decimal places is 2 and that should be the number of digits to the right of the decimal point in the result.
Then the result of the sum should be 9.66 × 10-3 g
I got 2.......................