10/28/20

Which would emit the lowest frequency?

Which energy transition would emit a photon with the lowest frequency of light in a hydrogen-like atom? n=2 to n=3n=3 to n=9n=8 to n=5n=4 to n=2

Messages to Tutors Not Showing Up in Inbox

I'm messaging various tutors, but they aren't showing up in my inbox. Are the messages going through? Please help!!

09/23/20

. Complete the following table.

isotope, atomic number, mass number, number of protons, number of neutrons 236/92 U 94/43 Tc

09/23/20

Calculate the half-life of the radioisotope

4. A 160. mg sample of radium-224 weighs 20.0 mg after 9.0 years. Calculate the half-life of the radioisotope.

Biology Question

How many grams of NaCl would you dissolve in water to make a 500 mM NaCl solution with 1-liter final volume ?

Biology Question

How much milliliters of absolute ethanol (100% ethanol) would you mix with how much milliliter of pure water to make 100ml of 70% (v/v) ethanol solution ?

01/19/20

What is a mass spectrum?

01/10/20

You produce 0.36 g hydrogen gas using 15 g copper(II). What is your percent yield?

Cu+H2SO4–>? partial answer: 7X.XX%

01/08/20

What will happen if the concentrations of Ca and HCl are increased?

The equation below shows the reaction of calcium (Ca) with hydrochloric acid (HCl). Ca (s) + 2 HCl (aq) → CaCl2 (aq) + H2 (g)

12/10/19

Volume Occupying STP

What volume does 1.5 x 1024 molecules of CO2 occupy at STP?

12/09/19

How do you criss cross a compound with four elements in it?

For example, folic acid and Thiamine mononitrate

12/08/19

Chemistry question

1a. Consider the following reaction:2HBr(aq)+Sr(OH)2(aq) → 2H2O(l)+SrBr2(aq)Enter the complete ionic equation for this reaction.Express your answer as a complete ionic equation. Identify all of the... more

12/03/19

Calculate the solubility

Calculate the solubility (in mol/L) of Co(OH)3 (Ksp = 3 ✕ 10−43) in each of the following. (Assume that all solutions are at 25°C. Enter unrounded values.) (a) water (assume pH is 7.0 and constant)... more

12/01/19

How many grams of calcium hydroxide are needed to neutralize 25 ml of 0.100 m hno3?

Please help very urgent

12/01/19

What is the molecular geometry shape and hybridization central atom for PF5, ClF3, CO2-3, SF-5, I-3?

How to find the molecular geometry shape and what are they to see if I got it correct as well as the hybridization of the central atom. Clear answer to all of them and what are the answers. I need... more
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