Answer:
<em>2.085 x 10^-20 J</em>
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Explanation:
minimum energy required to produce photoelectric effect in chromium is given as hf = 7.21 x 10^-19 J
The work function of chromium Ф = 4.37 eV = 7.00151 x 10^-19 J
The minimum energy required to eject an electron from from a chromium metal E = ?
From E = hf - Ф
substituting values, we have
E = (7.21 x 10^-19) - (7.00151 x 10^-19)
E = <em>2.085 x 10^-20 J</em>
Answer:
The answer is in the explanation
Explanation:
Single displacement reactions: In these reactions, a more reactive element kicks out a less reactive element from a compound.
Ex. Zn(s) + 2 HCl(aq) → ZnCl2(aq) + H2(g)
In this example, Zn is more reactive than H, then Zn displaces H from the compound.
Double displacement reactions: In these kind of reactions 2 elements are displaced from the different compounds, these elements interchange positions.
Ex. CuCl2(aq) + 2 AgNO3(aq) → Cu(NO3)2(aq) + 2 AgCl(s)
In the example, Cu displaces Ag and Ag displaces Cu, they interchange positions.
The two reason behind the invalidity of flame test are false positive and false negative.
while performing the flame test you must have to be accurate otherwise you will get false results may be positive for some element or may be negative in case the element is present. The main reason to get the false positive and false negative is the presence and contamination of sodium.
Answer:
3 to 5
Explanation:
The pH scale is from 0 to 14.
Acids have a pH of anything less than 7.
Anything with a pH greater than 7 is considered to be a base.
If a solution has a pH of 7, it is neutral.
3 to 5 is in the range of less than 7, so a solution of an acid can have this pH.
6 to 8 includes less than 7 , 7 and greater than 7, so it is not just in the range of an acid.
9 to 11 and 12 to 14 are both in the range of greater than 7, so they have to be bases.
Therefore, the correct answer is 3 to 5.
