The correct answer is the last option. Active metals will not react with acids in double replacement reactions. Instead, it reacts with metals via sing replacement reactions. It will displace hydrogen from the acid.
Explanation:
a.
→ ?
![Pb(NO_3)_2(aq) + Na_2SO_4(aq)\rightarrow PbSO_4(s)+2NaNO_3(aq)](https://tex.z-dn.net/?f=Pb%28NO_3%29_2%28aq%29%20%2B%20Na_2SO_4%28aq%29%5Crightarrow%20PbSO_4%28s%29%2B2NaNO_3%28aq%29)
![Pb(NO_3)_2(aq)\rightarrow Pb^{2+}(aq)+2NO_3^{-}(aq)](https://tex.z-dn.net/?f=Pb%28NO_3%29_2%28aq%29%5Crightarrow%20Pb%5E%7B2%2B%7D%28aq%29%2B2NO_3%5E%7B-%7D%28aq%29)
![Na_2SO_4(aq)\rightarrow 2Na^++SO_4^{2-}(aq)](https://tex.z-dn.net/?f=Na_2SO_4%28aq%29%5Crightarrow%202Na%5E%2B%2BSO_4%5E%7B2-%7D%28aq%29)
![Pb^{2+}(aq)+2NO_3^{-}(aq)+2Na^++SO_4^{2-}(aq)\rightarrow PbSO_4(s)+2Na^++2NO_3^{-}(aq)](https://tex.z-dn.net/?f=Pb%5E%7B2%2B%7D%28aq%29%2B2NO_3%5E%7B-%7D%28aq%29%2B2Na%5E%2B%2BSO_4%5E%7B2-%7D%28aq%29%5Crightarrow%20PbSO_4%28s%29%2B2Na%5E%2B%2B2NO_3%5E%7B-%7D%28aq%29)
Removing common ions from both sides, we get the net ionic equation:
![Pb^{2+}(aq)+SO_4^{2-}(aq)\rightarrow PbSO_4(s)](https://tex.z-dn.net/?f=Pb%5E%7B2%2B%7D%28aq%29%2BSO_4%5E%7B2-%7D%28aq%29%5Crightarrow%20PbSO_4%28s%29)
b.
→
![NiCl_2(aq) + NH4NO_3(aq) \rightarrow Ni(NO_3)_2+NH_4Cl(aq)](https://tex.z-dn.net/?f=NiCl_2%28aq%29%20%2B%20NH4NO_3%28aq%29%20%5Crightarrow%20Ni%28NO_3%29_2%2BNH_4Cl%28aq%29)
No precipitation is occuring.
c.
→
![FeCl_2(aq) + Na_2S(aq)\rightarrow FeS(s)+2NaCl(aq)](https://tex.z-dn.net/?f=FeCl_2%28aq%29%20%2B%20Na_2S%28aq%29%5Crightarrow%20FeS%28s%29%2B2NaCl%28aq%29)
![FeCl_2(aq)\rightarrow Fe^{2+}(aq)+2Cl^{-}(aq)](https://tex.z-dn.net/?f=FeCl_2%28aq%29%5Crightarrow%20Fe%5E%7B2%2B%7D%28aq%29%2B2Cl%5E%7B-%7D%28aq%29)
![Na_2S(aq)\rightarrow 2Na^++S{2-}(aq)](https://tex.z-dn.net/?f=Na_2S%28aq%29%5Crightarrow%202Na%5E%2B%2BS%7B2-%7D%28aq%29)
![Fe^{2+}(aq)+2Cl^{-}(aq)+2Na^++S^{2-}(aq)\rightarrow FeS(s)+2Na^++2Cl^{-}(aq)](https://tex.z-dn.net/?f=Fe%5E%7B2%2B%7D%28aq%29%2B2Cl%5E%7B-%7D%28aq%29%2B2Na%5E%2B%2BS%5E%7B2-%7D%28aq%29%5Crightarrow%20FeS%28s%29%2B2Na%5E%2B%2B2Cl%5E%7B-%7D%28aq%29)
Removing common ions from both sides, we get the net ionic equation:
![Fe^{2+}(aq)+S^{2-}(aq)\rightarrow FeS(s)](https://tex.z-dn.net/?f=Fe%5E%7B2%2B%7D%28aq%29%2BS%5E%7B2-%7D%28aq%29%5Crightarrow%20FeS%28s%29)
d.
→
![MgSO4(aq) + BaCl2(aq)\rightarrow BaSO_4(s)+MgCl_2](https://tex.z-dn.net/?f=MgSO4%28aq%29%20%2B%20BaCl2%28aq%29%5Crightarrow%20BaSO_4%28s%29%2BMgCl_2)
![MgSO_4(aq)\rightarrow Mg^{2+}(aq)+SO_4^{2-}(aq)](https://tex.z-dn.net/?f=MgSO_4%28aq%29%5Crightarrow%20Mg%5E%7B2%2B%7D%28aq%29%2BSO_4%5E%7B2-%7D%28aq%29)
![BaCl_2(aq)\rightarrow Ba^{2+}+2Cl^{-}(aq)](https://tex.z-dn.net/?f=BaCl_2%28aq%29%5Crightarrow%20Ba%5E%7B2%2B%7D%2B2Cl%5E%7B-%7D%28aq%29)
![Mg^{2+}(aq)+SO_4^{2-}(aq)+Ba^{2+}+2Cl^{-}(aq)(aq)\rightarrow BaSO_4(s)+Mg^{2+}(aq)+2Cl^{-}(aq)](https://tex.z-dn.net/?f=Mg%5E%7B2%2B%7D%28aq%29%2BSO_4%5E%7B2-%7D%28aq%29%2BBa%5E%7B2%2B%7D%2B2Cl%5E%7B-%7D%28aq%29%28aq%29%5Crightarrow%20BaSO_4%28s%29%2BMg%5E%7B2%2B%7D%28aq%29%2B2Cl%5E%7B-%7D%28aq%29)
Removing common ions from both sides, we get the net ionic equation:
![Ba^{2+}(aq)+SO_4^{2-}(aq)\rightarrow BaSO_4(s)](https://tex.z-dn.net/?f=Ba%5E%7B2%2B%7D%28aq%29%2BSO_4%5E%7B2-%7D%28aq%29%5Crightarrow%20BaSO_4%28s%29)
The molar mass of the unknown compound is <u>223.2 g/mol.</u>
<u />
Solution:
Molarity = ![\frac{Weight}{molecularweight} * \frac{1000}{Volume (ml)}](https://tex.z-dn.net/?f=%5Cfrac%7BWeight%7D%7Bmolecularweight%7D%20%20%2A%20%5Cfrac%7B1000%7D%7BVolume%20%28ml%29%7D)
![4.54*10^{-4} = \frac{0.0152g}{molecularweight} * \frac{1000}{150.ml}](https://tex.z-dn.net/?f=4.54%2A10%5E%7B-4%7D%20%3D%20%5Cfrac%7B0.0152g%7D%7Bmolecularweight%7D%20%2A%20%5Cfrac%7B1000%7D%7B150.ml%7D)
Molecular weight =<u> 223.2 g/mol</u>
<u />
The main difference between the two is that molar mass refers to the mass of one mole of a particular substance. Molecular weight is the mass of a molecule of a particular substance. Although the definitions and units of molar mass and molecular weight are different, the values are the same.
The formula mass of a molecule is the sum of the atomic weights of the atoms in that molecular formula. The molecular weight of a molecule is the average mass calculated by adding the atomic weights of the atoms in the molecular formula. Molecular weight is the mass of a single molecule, specifically the mass of material required to make a single mole.
Learn more about Molecular weight here:-brainly.com/question/26388921
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Answer:
This question is somehow not clear, because a typical human eye can notice objects which have wavelengths from about 380 to 740 nanometers. This is called visible spectrum (the portion of the electromagnetic spectrum that is visible to the human eye). Electromagnetic radiation in this range of wavelengths is called visible light or simply light.
Someone even can see extra colors - they able to see beyond the visible spectrum. The reason that the human eye can see the spectrum is because those specific wavelengths stimulate the retina in the human eye. The human retina can only detect incident light that falls in waves from about 380 to 740 nanometers long, so we can’t see microwave or ultraviolet wavelengths. This also applies to infrared lights which has wavelengths longer than visible and shorter than microwaves, thus being invisible to the human eye.
In conclusion, the human eye can not notice that objects with wavelength not in the range of 380 to 740 nanometers.
Explanation: