Explanation:
1 mole of a gas has 22.4 L of volume at STP. Therefore, 0.5 mol of H2 has 0.5 x 6.022 x 1023 = 3.011 x 1023 molecules. Hence, the number of moles, molecules and atoms present in 11.2 liters of H2 at STP are 0.5 , 3.011 x 1023 and 6.022 x 1023 respectively.
Answer is: formula of hydrate is CoCl₂· 6H₂O -c<span>obalt(II) chloride hexahydrate
</span>m(CoCl₂· xH₂O) = 1,62 g.
m(CoCl₂) = 0,88 g.
n(CoCl₂) = m(CoCl₂) ÷ M(CoCl₂)
n(CoCl₂) = 0,88 g ÷ 130 g/mol
n(CoCl₂) = 0,0068 mol.
m(H₂O) = 1,62 g - 0,88 g.
m(H₂O) = 0,74 g.
n(H₂O) = m(H₂O) ÷ m(H₂O)
n(H₂O) = 0,74 g ÷ 18 g/mol
n(H₂O) = 0,041 mol.
n(CoCl₂) : n(H₂O) = 0,0068 mol : 0,041 mol.
n(CoCl₂) : n(H₂O) = 1 : 6.
Answer:
D. First, put the specimen into focus using a low power lens, then switch to a higher power lens, if needed.
Explanation:
The microscope is a delicate and very useful and necessary instrument in a laboratory. For this reason, it must be used with care and responsibility so as not to compromise its operation.
To use a microscope it is necessary, first, that the sample to be observed is prepared. After that, you must turn on the device and place the sample in the appropriate place and try to focus the image using the low power objective lens. When the image is properly focused, you can use the high-power lens.