When a particular solid sample is examined under a microscope it is observed that there are regions which are black and regions which are yellow. What type of material is this sample?
A) a compound
B) an element
C) a homogeneous mixture
D) a heterogeneous mixture
D
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Which two languages began as trade languages in Sub-Saharan Africa and are now the most widely used languages in their respective regions?
A) Swahili and Yoruba B) Swahili and Hausa C) Spanish and Portuguese D) Arabic and French E) French and English
Current ethanol production in Brazil is different from ethanol production in the United States because in Brazil,
A) special enzymes that break down cellulose into sugars are used. B) ethanol is used to heat homes and generate electricity. C) sugar cane is used instead of corn. D) natural gas is used to generate ethanol.
In addition to increasing atmospheric levels of carbon dioxide, humans are negatively impacting coral reefs by ________
A) overharvesting fish and invertebrates that live in reef ecosystems B) introducing alien species that are thought to be more productive C) destroying large regions of coral reefs for commercial aquaculture D) using large amounts of coral rock to pave roads and build houses
A structure built perpendicular to shore to enlarge a beach or prevent erosion is a(n)
____________________. Fill in the blank(s) with the appropriate word(s).