Answer is: a) in the presence of a base.
Phenolphthalein is colorless in acidic solutions and pink in basic solutions.
Acid-base indicators are usually weak acids or bases and they are chemical detectors for hydrogen or hydronium cations.
Example for acid-base indicator is phenolphthalein (molecular formula C₂₀H₁₄O₄).
When solution turns phenolphthalein pink, it means it is basic (pH>7).
The alpha particle is the helium nucleus.
The mass of helium nucleus (⁴₂He) is 4u.
The mass of radioactive atom decreases by 4u. Look at the reaction below:
²²³₈₈Ra ---> ⁴₂He + ²¹⁹₈₆Rn
Answer:
to go against dangerous viral and bacteria
Explanation:
A beta particle is an electron and it has a -1 charge and zero mass.
Beta decay by
emitting an electron is called as β⁻
decay. When this happens, a neutron of the element converts into a proton by
emitting an electron. Hence, the mass of daughter nucleus is same as parent
atom but atomic number/number of protons is higher by 1 than atomic number of
parent atom.
In a β⁻ decay, the symbol is used as ₋₁⁰β or ₋₁⁰e.
-1 is for charge
<span> 0 is for the mass of the particle
</span>
The molar extinction coefficient is 15,200 
.
The formula to be used to calculate molar extinction coefficient is -
A = ξcl, where A represents absorption, ξ refers molar extinction coefficient, c refers to concentration and l represents length.
The given values are in required units, hence, there is no need to convert them. Directly keeping the values in formula to find the value of molar extinction coefficient.
Rewriting the formula as per molar extinction coefficient -
ξ = 
ξ = 
Performing multiplication in denominator to find the value of molar extinction coefficient
ξ = 
Performing division to find the value of molar extinction coefficient
ξ = 15,200
Hence, the molar extinction coefficient is 15,200 .
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