An index fossil is a fossil that is useful for dating and correlating the strata in which it is found.
Or it is a fossil that helps you find the date where it has been found. I rephrased that.
climate
Changes in the composition of the atmosphere have caused gradual changes in earth's <u>climate</u> throughout history, causing changes in plant and animal life that contributed to mass extinctions.
The following are some of the reasons:
- UV light
- climate
- pollutants
- hydrofluorocarbons
heat
- The surface of the Earth warms up as sunlight strikes it.
- Surface-emitted infrared light is absorbed in the atmosphere and transformed into heat.
- The temperature close to the surface rises as a result of this heat being trapped in the atmosphere.
<h3>UV light:</h3>
- indirect impacts of climate change on UV radiation from the surface.
- By changing the concentrations of ozone, UV-absorbing tropospheric gases, aerosols, and clouds in the atmosphere, climate change may have indirectly affected UV radiation levels in the past.
- These influences are probably going to persist in the future.
<h3>climate:</h3>
- People are at risk from food and water shortages, greater flooding, high heat, an increase in disease, and economic loss due to climate change.
- Conflict and human migration are potential outcomes.
- Climate change is the top hazard to world health in the twenty-first century, according to the World Health Organization (WHO).
<h3>pollutants:</h3>
- these are also resulting in the increase of temperature of the Earth and is also damaging ozone layer.
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First find the oxidation states of the various atoms:
<span>in Cr2O2 2- Cr @ +1; In NH3 N @ +3; in CrO3 Cr @ +3, N2 N @ 0 </span>
<span>Note that N gained electrons, ie, was reduced; Cr was oxidized </span>
<span>Now there is a problem, because B has NH4+ which the problem did not, and is not balanced, showing e- in/out </span>
<span>B.NH4+ → N2 </span>
<span>Which of the following is an oxidation half-reaction? </span>
<span>A.Sn 2+ →Sn 4+ + 2e- </span>
<span>Sn lost electrons so it got oxidized</span>
Answer:
Starch is a viable indicator in the titration process because it turns deep dark blue when iodine is present in a solution. When starch is heated in water, decomposition occurs and beta-amylose is produced
There are 1.2 hr would this current have to be applied to plate out 7. 20 g of iron .
Calculation ,
Given ; Current ( I ) = 5. 68 A
In 
, the valancy of Fe is +2 .
2 moles of 
are required for the decomposition of 1 mole of Fe .
7. 20 g of Fe in moles = 7. 20 g /55.845 g/mol =0.12 mole
x moles of are required for the decomposition of 0.128 mole of Fe .
moles of are required = 0.256 moles
Charge on 1 mole of = 96500 C
Charge on 0.256 mole of = 24704 C
Current ( I )= Q/t
t =Q / I = 24704 C/5. 68 A = 4349 sec = 1.2 hr
Therefore , there are 1.2 hr would this current have to be applied to plate out 7. 20 g of iron .
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