For each of the following pairs, circle the one that is largest: a. 1000 m 1 km

Question

For each of the following pairs, circle the one that is largest: a. 1000 m 1 km b. 1 cm 100 mu m Answer each of the following: a. How many mg are there in 122 mu g? b. The wavelength of green light is about 525 nm. How many cm is this? The density of copper is 8.92 g/cm^3. What volume in mL of copper will have a mass of 22.5 mg? How many significant figures can you have in your answer? One isotope of sodium is sodium-25. How many neutrons does this isotope contain? Write the designation for this isotope (containing 10 electrons) using the format: Give the electron configuration for a neutral atom of sulfur: Give the electron configuration for the ion, K. The compound NCl_3 is known to exist. Using the periodic table, give another example of a 1 to 3 compound that doesn't involve nitrogen or chlorine. Which of the three colors, red, green, orange, has the higher energy. Which has the longest wavelength?

Explanation / Answer

1a) 1000mm = 0.001km. So 1km>0.001Km . Answer is 1Km.

b) 100um= 0.01cm. So 1cm>0.01cm. Answer is 1cm.

2 a) 1mg = 1000ug; 122ug has 0.122mg.

b) 1nm = 10-7 cm; converting 525nm to cm?

525 x 10-7 cm or 5.25 x 10-5 cm.

3) from the formula density = mass/ volume

given density = 8.92g cm-3 , mass = 22.5 mg, volume in ml = ?

volume = mass/density ;   converting 22.5mg to g which gives 0.0225g (1mg= 0.001g)

volume = 0.0225/ 8.92 = 0.0025 ml or 2.5 x 10-3 ml or ronding off to 0.003 ml

one can have upto three significant figures after a decimal.

4) Sodium - 25 has an atomic mass of 25 and atomic number is 11 which indicates 11 protons are there . So

25 - 11 = 14. 14 neutrons are there . It is different from from regular sodium because its heavier and radioactive.

representing in isotopic notation ZAXC which indicates X is the symbol of the element, A - mass number(no of protons + neutrons), Z- atomic number (no. of protons), C - net charge

      2511Na +1 is the notation. since 10 electrons are given and total protons are 11, net charge is +1.

5) Elemental Sulphur is also known as neutral sulphur . The electronic configuration is given as below:

S- 1s2 2s2 2p6 3s2 3p4

6) K+ - 1s2 2s2 2p6 3s23p6 (18 electrons)

7) CF3 - tri fluoromethyl

8) As we go down the electro magnectic spectrum table the energy decreases and wavelength increases hence green has highest energy and red has longest wavelength.

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