Answer:
Option-B (Carbon and Silicon)
Explanation:
Among the given pairs only carbon and silicon have the most similar properties. This is because,
Sodium and Magnesium belong to different groups. Sodium present in Group I has one electron in its valence shell and capable of transferring only one electron while, Magnesium present in Group II have two electrons in its valence shell and is capable of donating two electrons. Hence, both show different properties.
Example:
2 Na + Cl₂ → NaCl
Mg + Cl₂ → MgCl₂
As shown in reactions when Sodium and Magnesium are treated with Cl₂ they give a products with different proportions.
Carbon and Silicon show almost same properties because both belong to Group IV hence both are capable of forming four bonds. Also, they share the same property of self linkage in making a long chains.
Argon and Chlorine also belong to two different groups. Argon is present in Group VIII (Noble Gases) and Chlorine is present in Group VII (Halogens). Hence, Argon is an inert specie which is non reactive while Chlorine gives different reaction easily.
Potassium and Calcium belong to different groups. Potassium present in Group I has one electron in its valence shell and capable of transferring only one electron while, Calcium present in Group II have two electrons in its valence shell and is capable of donating two electrons. Hence, both show different properties.
Example:
2 K + Cl₂ → KCl
Ca + Cl₂ → CaCl₂
As shown in reactions when Potassium and Calcium are treated with Cl₂ they give a products with different proportions.
Bromine +
Chlorine
Bromide +
Potassium
Chloride
Bromine +
Potassium
Chloride
Hydrogen
bromide +
Potassium
Chloride
Chlorine +
Potassium
Bromide ->
blue end of the spectrum
middle of the spectrum
The light-gathering capacity of a telescope is dependent upon the:
magnification
focal length
size of human iris
area of aperture
Answer:
1) blue end of the spectrum
2) area of aperture
Explanation:
1) The electromagnetic spectrum encompases a wide range of frequency (ν) and wavelength (λ) that includes gamma rays, x-rays, ultra violet(UV), visible, infra red (IR), microwaves and radiowaves. The wavelength increases from gamma rays to radio waves.
The wavelength perceivable by human eyes lies in the UV-visible region which extends from 380 nm in the blue to 740 nm in the red.The shortest wavelengths occur in the blue end of the spectrum which also have the highest energy. In contrast, longer wavelengths occur on the red which have lower energy.
2) The light gathering capacity of a telescope is dependent upon its area of aperture. Larger the area, greater is the light gathering power which implies that the telescope has the capability of detecting weak or faint objects.
The area of the aperture is essentially the area of the objective of the telescopic lens which is given as:
where D = diameter of the lens
1) blue end of the spectrum
2) area of aperture
The weight of oxegon
Answer:
85g
Explanation:
To convert the moles of a substance to grams we need to know the molar mass of the substance. We, as first, must obtain the molar mass of (NH₄)₂S as follows:
There are 2 atoms of N, 8 of H and 1 of S:
N = 2*14g/mol = 28g/mol
H = 8*1g/mol = 8g/mol
S = 1*32g/mol = 32g/mol
Molar mass: 68g/mol
That means 1 mole of (NH₄)₂S has a mass of 68g.
1.25moles have a mass of:
1.25moles * (68g/mol) =
The specific heat of the unknown sample has been .
Specific heat has been defined as the amount of heat required to raise the temperature of 1 gram of substance by 1 degree Celsius.
The specific heat (c) for a substance can be given by:
......(i)
Where, the heat required by the substance,
The mass of the substance has been,
The change in temperature of the system has been,
The change in temperature has been given as:
The initial temperature of the substance,
The final temperature of the substance,
Substituting the values for the change in temperature, :
Substituting the values in equation (i):
The specific heat of the unknown sample has been .
For more information about specific heat, refer to the link:
B. Water molecules slow done until they begin to form stronger bonds together.
C. As water molecules cool, their shape changes from rounded to irregular, making them more likely to link to one another
D.Water molecules are squeezed together by high pressure until they begin to stick to one another.
The correct option is B.
When the temperature of water is reduced, the water cools down and the molecules of the water lose energy and move slowly. As the water is cooling down its volume expands. When the temperature of the water reaches zero degree Celsius, the molecules of the water stick together and form solid ice, thus turning from a liquid state to a solid state.