. periodic table * sub-shell
Diagrammatic questions
What factors do the valencies of elements depend upon?
A part of a periodic table is given below. Study it and answer the follow
ii. Sketch the atomic structure of that element which is placed in period 3
vi. transition element
IIA
IVA
IIIA
IA
VA
Be B. С N
Li
O
Periods 2
Mg
Si
Al
3. Na
Р S СІ
i Write the names of two very reactive non-metals.
questions.
VIA VIIA
O
Ne
F
Ar
has valency 4.
ii. Name the most reactive metal with a suitable reason.
study the given electronic configuration of the elements and answer the follo
questions.
A. 2,8,1 B.2,8 C. 2,8,7 D. 1

A3.37-mg sample of protein was chemically digested to convert its nitrogen into ammonia and then diluted to 100.0 ml. then 10.0 ml of this solution was placed in a 50-ml volumetric flask and treated with 5 ml of phenol solution plus 2 ml of sodium hypochlorite solution. the sample was diluted to 50.0 ml, and the absorbance at 625 nm was measured in a 1.00-cm cuvette and found to be 0.486. for reference, a standard solution was prepared from 10.0 mg of nh4cl (molar mass = 53.49 grams/mole) dissolved in 1.00 l of water. then 10.0 ml of this standard was placed in a 50-ml volumetric flask, treated in the same manner as the unknown, and the absorbance found to be 0.323. finally, a reagent blank was prepared using distilled water in place of unknown, it was treated in the same manner as the unknown, and the absorbance found to be 0.076. calculate the weight percent of nitrogen in the protein.

Which of the following is not an assumption that scientists must make about the natural world? a. regularity b. causality c. predictability d. plausibility

Which would freeze at a higher temperature: the great salt lake or lake tahoe? a. lake tahoe would freeze at a higher temperature. b. the great salt lake would freeze at a higher temperature. c. both lakes would freeze at the same temperature.