The number 0.000430 expressed in scientific notation to the correct number of si

Question

The number 0.000430 expressed in scientific notation to the correct number of significant figures becomes___________. Write the symbol (abbreviation) for each of the following metric system units: microgram, kilometer, milliliter, decisecond, and centiliter What mass of NaOH is needed to produce 22.0 mL of 1.3 M solution? A solution is made by dissolving 2.60 mole of KBr in enough water to give a final volume of 1030 mL. What is the molarity of the solution? What volume of a solution with a density of 13.9 g/mL is needed to provide 311 grams of solution? 533 quarts is equivalent to how many microliters? (1 gallon- 3.79L, 4 quarts=1 gallon) Which of the following test results would be classified as a chemical property of the substance? It reacts with base to form water. Its density is 1.84 g/mL. It tastes sour. It is a white-colored solid. A pure substance has been isolated in the laboratory. Based on the two characteristics below, how can the substance be classified? The species cannot be separated by physical means. The species can be separated by chemical means. an element a compound a homogeneous mixture a heterogeneous mixture Between elements and compounds, which ones are pure substances/give the symbol for the following elements: silver, gold, mercury, potassium, zinc, bromine, copper, helium, neon cobalt, chromium, sodium, argon, iron, lead, sulfur, aluminum, cobalt, chlorine, iron, lithium nickel, zinc, potassium, hydrogen, fluorine, phosphorous What difference in meaning is there in notations of CoBr_2 and COBr_2? definition of "molecule" classification of elements: group IA is alkali, group IIA, VIA, VIIA, VIIIA, B goups? Each end with which subshell (spdf)

Explanation / Answer

1)

it becomes 4.3 x 10-4

2)

microgram --> ug

kilometer --> km

milliliter ---> ml

decisecond --> ds

centiliter --> cl

3)

we know that

moles = molarity x volume (ml) / 1000

moles of NaOH = 1.3 x 22 / 1000 = 0.0286

now

mass = moles x molar mass

mass of NaOH = 0.0286 x 40

mass of NaOH = 1.144

so

1.144 grams of NaOH is needed

4)

molarity = moles x 1000 / volume (ml)

molarity = 2.6 x 1000 / 1030

molarity = 2.524

so

the molarity of the solution is 2.524 M

5)

we know that

volume = mass / density

volume = 311 / 13.9

volume = 22.374

so

22.374 ml of the solution is needed

6)

volume = 533 quarts

= 533/ 4 gallon

= 133.25 gallon

= 133.25 x 3.79 L

= 505.0175 L

= 5.05 x 10^8 x 10-6 L

= 5.05 x 10^8 uL

so

the 533 quarts is 5.05 x 10^8 uL

7) A) it reacts with base to form water

8) D) a homogenous mixture

9) elements are pure substances

10)

silver --> Ag

gold---> Au

mercury --> Hg

potassium --> K

zinc --> Zn

bromine --> Br

copper --> Cu

helium --> He

neon --> Ne

cobalt --> Co

chromium ---> Cr

sodium ---> Na

argon ---> Ar

iron --> Fe

lead ---> Pb

sulfur --> S

aluminium --> Al

cobalt ---> Co

chlorine ---> Cl

lithium ---> Li

nickel ---> Ni

hydrogen --> H

flourine --> F

phosphorus --> P

11)

CoBr2 ---> Cobalt bromide

COBr2 --> carbonyl bromide

12)

groups of atoms bonded together

14) group II A --> alkaline earth , S

VI A --> chalcogen , P

VIIA --> halogen , P

VIIIA --> noble gases , P

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