* not completed

. Which one(s) of these statements is/are true? (Please select all that apply)

Log K_ow for fat-soluble organic species tend to be large values correct incorrect

A correlation is expected between log K_ow and log BCF correct incorrect

A large LD₅₀ value signifies high toxicity correct incorrect

R_f values are inversely related to log K_om correct incorrect

A low R_f value indicates a high mobility in a soil for a pesticide correct incorrect

* not completed

. Which one(s) of these statements is/are true? (Please select all that apply)

Degradation t_1/2 values for organophosphorus pesticides are generally greater than those for organochlorine pesticides correct incorrect

For a pesticide, a high R_f value signifies high mobility in soil correct incorrect

For a pesticide, a high log K_om signifies high mobility in soil correct incorrect

Leachability of a pesticide depends on both its half-life and its K_om correct incorrect

Vaporization is not considered as an aspect of pesticide mobility in a soil correct incorrect

* not completed

. Which one(s) of these statements is/are true? (Please select all that apply)

K_omf_om  = K_ocf_oc correct incorrect

K_d = K_om x f_om correct incorrect

K_oc = K_om x 1.7 correct incorrect

K_d = f_om x C_om / C_aq correct incorrect

K_d = 1/R_f correct incorrect

* not completed

. Which of the following properties of biocides is/are true? (Please select all that apply)

Chlorine in an organic compound usually enhances its chemical stability correct incorrect

Dermal LD₅₀ and LC₅₀ values are usually higher than are oral values correct incorrect

The leachability of compounds is connected with their chemical stability correct incorrect

Oxygen-containing organophosphorus pesticides are more toxic than their sulfur-containing analogues correct incorrect

The reaction products of some pesticides are more toxic than the parent compound correct incorrect

* not completed

. Which of the following statements about degradation of biocides is/are true?  (Please select all that apply)

Molecules that absorb radiation of wavelengths <250 nm and have small bond enthalpy values are subject to photolytic degradation by sunlight correct incorrect

Direct photolytic reactions follow first-order or pseudo-first-order kinetics correct incorrect

The rate of indirect photolysis is given by rate = f[sensitizer][receptor] correct incorrect

Hydrolysis at the phosphorus centre of organophosphorus compounds is a common reaction correct incorrect

Hydrolysis of biocides is a purely abiotic process correct incorrect

* not completed

. Which of the following statements about degradation of biocides is/are true? (Please select all that apply)

Biologically mediated oxidation is a common process by which hydrocarbons are degraded correct incorrect

A high pE environment favours dehalogenation or halogenated organic compounds correct incorrect

Low molar mass hydrocarbons decompose more rapidly than high molar mass ones correct incorrect

At field capacity, many degradation reactions in soil occur at their optimum rate correct incorrect

High organic matter content in a soil often inhibits degradation of organic biocides correct incorrect

* not completed

. Which of the following statements about environmental behaviour of biocides is/are true? (Please select all that apply)

The grasshopper effect describes how semi-volatile biocides move from place to place depending on wind currents correct incorrect

The GUS index combines information about toxicity and degradative half-life of a biocide correct incorrect

A plot of equilibrium vapour pressure of a biocide vs water content of a soil often increases to a plateau as soil moisture content increases correct incorrect

It is commonly found that log K_OA values increase linearly with temperature correct incorrect

K_om and R_f values are inversely related correct incorrect

* not completed

. Which of the following statements about environmental behaviour of biocides is/are true? (Please select all that apply)

The oral LD₅₀ for a pesticide in water uses units of mg (pesticide) L^-1 (water) correct incorrect

Organochlorine compounds often have a very large LD₅₀ value, indicating high toxicity correct incorrect

Intraparticle diffusion can frequently inhibit leaching of a biocide correct incorrect

Biocides with cationic components usually have limited mobility in soils correct incorrect

Organic matter in soil is one factor that encourages retention of biocides correct incorrect

* not completed

. Which of the following chemicals belong to the category euphemistically known as 'the dirty dozen' persistent organic pollutants (POPs)? (Please select all that apply)

Dioxins and furans correct incorrect

PAHs correct incorrect

Perfluorooctane sulfonic acid (PFOS) correct incorrect

Toxaphene, aldrin, endrin correct incorrect

DDT, PCBs, hexachlorobenzene correct incorrect

* not completed

. Based on the data in Table 20.6, which of the following is a currently used controversial pesticide having a pseudo first-order decay constant of approximately 1.1x10^-7 s^-1?

Metolachlor correct incorrect

Carbaryl correct incorrect

Heptachlor correct incorrect

Atrazine correct incorrect

Chlorpyrifos correct incorrect