<u>Answer:</u>
2.07 grams
<u>Explanation:</u>
We know that the molecular mass of 
is 138.205 grams.
In order to find out how many grams we need to make 200 mL having a potassium ion concentration of 0.150, we need to find the number of moles first.
M = moles / liters
0.150 = x / 0.200
x = 0.03 moles
Since there are 2 potassium atoms in each molecule of so we will divide this number by half and multiply it by the molecular mass.
0.03/2 = 0.015 moles
Mass of needed = 0.015 × 138.205 = 2.07 grams
The screen will not be useful in separating the mixture of saw dust, salt and pebbles.
Answer: Option C
<u>Explanation:
</u>
The separation of individual elements from the mixture can be done easily if the size of the elements in the mixture is varying significantly. Just like in the present case, the size of sawdust and salt is very small compared to that of pebbles.
So by using sieves having pores of smaller sizes, pebbles can be separated from the mixture as pebbles will not pass through the minute pores. Even depending upon the size of pores, the saw dust can also be separated using it.
Similarly, we can use water also to separate this mixture as sawdust have least density it will float in water surface and pebbles being the highest density will sink and settle in the bottom of the container.
Remaining salt will get dissolved in water which can be obtained by heating the water in order to precipitate the salt. Even filter paper with different mess size will also help in separating this mixture. But as this mixture is not permeable through screen, the screen cannot be used to separate this mixture.
Answer:700 nm corresponded to light in the red range and 450 nm corresponded to light in the blue range.
Explanation:The wavelengths of the visible spectrum are usually between 400 nm and 700 nmn with the the rays of red light having a longer wavelength, and blue light rays having shorter wavelengths. The red light has a low frequency of about 405–480 THz and , blue light has a higher frequency in the range of 620–680 THz. This is due to the inverse relationship between wavelength and frequency which also occurs betwwn wavelength and energy of light rays with the red light having less photon energy of about 1.65–2.00 eV and the blue light with high energy photons of about 2.64–2.75 eV.
Red light can be employed in the photosynthesis in plants as it helps in formation of flowers and the production of fruits. Blue light also is important in the production of chlorophyll and can cause a healthy and strong stem and leaves in excess exposure.
Answer:
B. A covalent bond has a lower potential energy than the two separate atoms.
Explanation:
<em>Identify the correct statement. </em>
<em>A. It is not possible for two atoms to share more than two electrons.</em> FALSE. Atoms also can share 4 electrons (double bond) or 6 electrons (triple bond).
<em>B. A covalent bond has a lower potential energy than the two separate atoms.</em> TRUE.
<em>C. Single bonds are shorter than double bonds.</em> FALSE. Single bonds are longer than double bonds.
<em>D. A covalent bond is formed through the transfer of electrons from one atom to another.</em> FALSE. In covalent bonds, electrons are shared, not transferred from one atom to another.
<em>E. A pair of electrons involved in a covalent bond are sometimes referred to as lone pairs.</em> FALSE. Lone pairs are those that do not participate in a bond.
Answer:
98.4 kPa
Explanation:
Step 1: Given and required data
- Partial pressure of water vapor at 60°C (pH₂O): 19.9 kPa (this info is tabulated)
- Partial pressure of nitrogen (pN₂): 53.0 kPa
- Partial pressure of helium (pHe): 25.5 kPa
Step 2: Calculate the total pressure of the gaseous mixture
The total pressure of the gaseous mixture (P) os equal to the sum of the partial pressures of the gases that form it.
P = pH₂O + pN₂ + pHe
P = 19.9 kPa + 53.0 kPa + 25.5 kPa = 98.4 kPa
