Answer:
Bismuth
Explanation:
In 1869 Mendeleev published his first Periodic System ending with Bismuth.
In 1871 he updated his system to end with Uranium.
Answer:
neutron
Explanation
neutrons have no net charge
In a food chain we arrange the energy in the form of a pyramid.
The producers are on the base of pyramid and then consumers are towards peak.
in the given food chain grass is being eaten by grasshopper which are food of birds.
Grasshoppers are also eaten up by Hawks. so both brids and hawks are feeding upon grasshoppers thus the amount of energy transferred from the grass to the grasshopper is the same as the amount of energy transferred from the grasshopper to the bird.
Answer:
True
Explanation:
Significant digits include non-zero digits (unless the zero is between two non-zero numbers)
In 12,785.000, there are 5 non-zero digits:
1 2 7 8 5
Answer: 69.72 kg of cryolite will be produced.
Explanation:
The balanced chemical equation is:
![Al_2O_3(s)+6NaOH(l)+12HF(g)\rightarrow 2Na_3AlF_6+9H_2O](https://tex.z-dn.net/?f=Al_2O_3%28s%29%2B6NaOH%28l%29%2B12HF%28g%29%5Crightarrow%202Na_3AlF_6%2B9H_2O)
To calculate the moles, we use the equation:
![\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}](https://tex.z-dn.net/?f=%5Ctext%7BNumber%20of%20moles%7D%3D%5Cfrac%7B%5Ctext%7BGiven%20mass%7D%7D%7B%5Ctext%20%7BMolar%20mass%7D%7D)
moles of
= ![\frac{16.9\times 1000g}{102g/mol}=165.7moles](https://tex.z-dn.net/?f=%5Cfrac%7B16.9%5Ctimes%201000g%7D%7B102g%2Fmol%7D%3D165.7moles)
moles of
= ![\frac{57.4\times 1000g}{40g/mol}=1435moles](https://tex.z-dn.net/?f=%5Cfrac%7B57.4%5Ctimes%201000g%7D%7B40g%2Fmol%7D%3D1435moles)
moles of
= ![\frac{57.4\times 1000g}{20g/mol}=2870moles](https://tex.z-dn.net/?f=%5Cfrac%7B57.4%5Ctimes%201000g%7D%7B20g%2Fmol%7D%3D2870moles)
As 1 mole of
reacts with 6 moles of ![NaOH](https://tex.z-dn.net/?f=NaOH)
166 moles of
reacts with =
moles of ![NaOH](https://tex.z-dn.net/?f=NaOH)
As 1 mole of
reacts with 12 moles of ![HF](https://tex.z-dn.net/?f=HF)
166 moles of
reacts with =
moles of ![HF](https://tex.z-dn.net/?f=HF)
Thus
is the limiting reagent.
As 1 mole of
produces = 2 moles of cryolite
166 moles of
reacts with =
moles of cryolite
Mass of cryolite
= ![moles\times {\text {molar mass}}=332mol\times 210g/mol=69720g=69.72kg](https://tex.z-dn.net/?f=moles%5Ctimes%20%7B%5Ctext%20%7Bmolar%20mass%7D%7D%3D332mol%5Ctimes%20210g%2Fmol%3D69720g%3D69.72kg)
Thus 69.72 kg of cryolite will be produced.