Explanation:
Formula used for the radius of the orbit will be,
(in pm)
where,
= energy of orbit
= radius of orbit
n = number of orbit
Z = atomic number
a) The Bohr radius of an electron in the n = 3 orbit of a hydrogen atom.
Z = 1
476.1 pm is the Bohr radius of an electron in the n = 3 orbit of a hydrogen atom.
b) The energy (in J) of the atom in part (a)
is the energy of n = 3 orbit of a hydrogen atom.
c) The energy of an Li²⁺ ion when its electron is in the n = 3 orbit.
n = 3, Z = 3
is the energy of an Li²⁺ ion when its electron is in the n = 3 orbit.
d) The difference in answers is due to change value of Z in the formula which is am atomic number of the element..
Answer:
if multiple choice e. d. a. if not e.
Explanation:
D.Thermal expansion can cause the concrete to expand and crack.
Explanation:
Steel joints are often used in sections of concrete bridges because if concrete is used, thermal expansion can cause it to expand and in the process cracks.
- During a very hot day, as the temperature rises, materials begins to expand.
- Concrete does not have good expansivity
- When it expands, the structure breaks and cracks down.
- When metals like steel expands, when cooling they return back to their original position.
- this is why steel joints are added to bridges.
learn more:
Temperature and heat brainly.com/question/914750
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Density is mass over volume. The density of iron is given in g/cm³
we have to first convert g/cm³ to kg/dL.
1000 g = 1 kg and 100 cm³ = 1 dL
the mass of 1 cm³ = 1 g
the mass of 100 cm³ / 1 dL = 100 g
then mass of 1 dL in kg is = 100 g / 1000 g/kg = 0.1 kg
volume of 0.1 kg is 1 dL
therefore density of iron is 7.86 g/cm³ x 0.1 kg/dL / g/cm³ = 0.786 kg/dL
volume of iron having mass 0.786 kg is 1 dL
then volume of iron having a mass of 4.62 kg is - 1 dL / 0.786 kg x 4.62 kg = dL
volume of iron is 5.88 dL