Answer:
a) 1.866 × 10 ⁻¹⁹ J b) 3.685 × 10⁻¹⁹ J
Explanation:
the constants involved are
h ( Planck constant) = 6.626 × 10⁻³⁴ m² kg/s
Me of electron = 9.109 × 10 ⁻³¹ kg
speed of light = 3.0 × 10 ⁸ m/s
a) the Ek ( kinetic energy of the dislodged electron) = 0.5 mu²
Ek = 0.5 × 9.109 × 10⁻³¹ × ( 6.40 × 10⁵ )² = 1.866 × 10 ⁻¹⁹ J
b) Φ ( minimum energy needed to dislodge the electron ) can be calculated by this formula
hv = Φ + Ek
where Ek = 1.866 × 10 ⁻¹⁹ J
v ( threshold frequency ) = c / λ where c is the speed of light and λ is the wavelength of light = 358.1 nm = 3.581 × 10⁻⁷ m
v = ( 3.0 × 10 ⁸ m/s ) / (3.581 × 10⁻⁷ m ) = 8.378 × 10¹⁴ s⁻¹
hv = 6.626 × 10⁻³⁴ m² kg/s × 8.378 × 10¹⁴ s⁻¹ = 5.551 × 10⁻¹⁹ J
5.551 × 10⁻¹⁹ J = 1.866 × 10 ⁻¹⁹ J + Φ
Φ = 5.551 × 10⁻¹⁹ J - 1.866 × 10 ⁻¹⁹ J = 3.685 × 10⁻¹⁹ J
Answer:
carbon-12 is not radioactive
Explanation:
The measurement of the age of dead carbon based life forms requires the use of a radioactive isotope hence it is often referred to as radiocarbon dating.
Carbon-12 and Carbon-14 occur together in living things.The half life of Carbon-14 is about 5670 years.
Hence, since Carbon-12 is not radioactive, it can not be used to measure the age of dead carbon based materials.
Answer:
Pure copper sulphate can be obtained from an impure sample by re-crystallization. The impure sample is dissolved in water, heated and then cooled which then later forms crystals. These copper sulphate crystals are then separated by filtration and drying.
The boiling point is the temperature at which the vapour pressure of the solution or solvent becuase equal to the ambient pressure, and bubbles of vapour from directly in the liquid. The normal boiling point is specified when the ambient pressure ( And also thvapour pressure of the boiling liquid) is One atmosphere. Ans so where strong intermolecular forces of attraction operate for instance in Hydrogen-Bonded liquids, boiling point should be elevated. More energy has to be put into the system to disrupt the intermolecular force. And the best indicator or intermolecular or inter-particle force is boiling point.
Through 100 ml of a one-molar sodium hydroxide solution, 896 ml (n.a.) of carbon dioxide was passed gas. Determine the mass solution of salt in the resulting solution. Density of a one-molar alkali solution, take equal to 1.04 g / ml.
