Chemistry - 2013 E.C (2020/2021) Ethiopian University Entrance Exam (EUEE)

A Silica is resistant to attack by all acids except HF, which it reacts to give SiF₄ and H₂O₂

B Silicon reacts with CH₃Cl at 300 °C in the Cu as a catalyst by further reactions with H₂O yields the polymer [(CH₃)₂SiO₂]_n

C Silicon occurs as silica (SiO₂) and silicate compounds containing the silicate ion (SiO₄^4-)

D Silica dissolves in hot molten Na₂CO₃ to give Na₄SiO₄ and CO₂

A analytical chemistry

B biochemistry

C inorganic chemistry

D physical chemistry

A measured values with the highest accuracy

B measured values with the highest precision

C exactly known digits with the last digit uncertain

D measured values with the highest uncertainty

A 1.5224 g/mL

B 1.5222 g/mL

C 3.5 g/mL

D 1.5 g/mL

A a method of arriving at an organized body of knowledge based on reproducible experiments and observations

B a collection of scientific guesses and hypotheses by seeking patterns in the observations

C the result of fortunate, accidental discovery in the development of science

D the sum total of unique guidelines for the practice of science in the world

A The person doing the experiment

B The type of material measured

C The environment where the measurement is made

D The measuring device

A the H-N, H-O and H-F bonds are less polar than ordinary covalent bonds

B the partially positive H of one molecule is attracted to the partially negative lone pairs on the N, O or F of another molecule

C the H-N, H-O and H-F bonds are non-polar and thus do not interact with neighboring molecules

D the small sizes of N, O and F makes these atoms so electropositive that their covalently bonded H is highly negative

A CCl₄

B NH₃

C PCl₅

D H₂O

A II and III

B I and III

C I and IV

D I and II

A the basic different structures of each hydride

B the small size of O compared to the other group VIA elements

C hydrogen bonding present in H₂O molecules

D increasing boiling points with increasing molecular mass