It’s because new discoveries are made all the time sometimes what was considered right may be found out to be wrong
Answer:
3.025eV
Explanation:
Energy of a photon is given by
E=hν
Where h is the Planck's constant
And ν represents the frequency of the photon .
Now for violet light wavelength λ=410nm= 410x10^-9m
By using the formula ν=c/λ
where c represents speed of light I.e 3 x 10^8 m/s
Calculating energy of violet photon we have
E=hc/λ
h=6.626 x 10^-34 J.s
On inserting the value in the formula , we get
E= 4.848 x 10^-19 Joules
To convert it into electron volts we need to divide it by 1.602 x10^-19.
The final result what we have is E=3.026eV.
Note: the result calculated is according to the above value . result may vary according to the values taken .
The definition of a gem is "a precious stone, cut and polished for jewelry. They are all minerals. Some highly desirable gemstones may not be suitable for jewelry, yet be very collectible, like sphene. Others, like those in the corundum family, are prized for color and hardness, like emeralds and diamonds. Further, some common minerals, when polished, make beautiful pieces. With all that said, i woukd go with rarer.
The question is in another language, so the English translation of the question is as follows:
Is salt-water a hom.ogeneous or heterogeneous mixture?
Answer:
Hom.ogenous mixture
Explanation:
There are two types of mixtures hom.ogenous and hetergenous. a heterogeneous mixture has two or more visible phases while a hom.ogeneous mixture is composed of a single visible phase.
The salt-water is hom.ogeneous because the solve dissolve evenly in throughout the entire salt-water sample and gives visible phase.
Hence, the correct option is "hom.ogenous mixture".
Answer:
Explanation:
A substance that produces an excess of hydroxide ion (-OH) in aqueous solution.
This is an arrhenius Base
According to the arrhenius theory, a base is a substance that combines with water to produce excess hydroxide ions, OH⁻ in an aqeous solution. Examples are :
- Sodium hydroxide NaOH
- Potassium hydroxide KOH
A substance that produces an excess of hydrogen ion (H+) in aqueous solution
This is an arrhenius Acid
An arrhenius acid is a substance that reacts with water to produce excess hydrogen ions in aqueous solutions.
Examples are;
- Hydrochloric acid HCl
- Hydroiodic acid HI
- Hydrobromic acid HBr
