Calamine, which is used for relief of skin irritations, is a mixture of zinc and iron oxides. A 1.056-g sample of dried calamine was dissolved in acid and diluted to 250.0 mL. Potassium fluoride was added to a 10.00-mL aliquot of the diluted solution to mask the iron; after suitable adjustment of the pH, Zn2+ consumed 38.37 mL of 0.01133 M EDTA. A second 50.00-Ml aliquot was suitably buffered and titrated with 2.30 mL of 0.002647 M ZnY2- solution: Fe3+ + ZnY2- → FeY- + Zn2+
Calculate the percentages of ZnC and Fe2C3 in the sample.

it is to be noted that an alpha particle is an helium nucleus. so it contains 2 protons 2 neutrons and has a mass number of 4. when alpha decay particles are ejected from the nucleus it gets transformed into an atom which has atomic number less than 2 and a mass number less than 4.

an equation that could represent alpha decay is radium 226 decay of alpha particle forms radon 222.

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your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.

for step 7 table c on the lab "newtons law of action"   the average time it took the car to travel .25 meters   was 1.92 seconds.

the average time it took the car to travel 0.50 meters was 2.61 seconds

hope this : )