Reconciling cash book and passbook differences

Correct answer: B. Because coarse particles settle quickly near the banks during floods

The correct answer is B. When floodwater spills over a river bank, its depth and velocity decrease suddenly. The heaviest and coarsest sand and silt particles therefore lose transport capacity first and settle close to the channel. Repeated floods build slightly raised embankments called natural levees. Fine material is carried farther onto the floodplain, so general river-bed uplift, wind, and glacier blockage do not explain levee formation.

Correct answer: C. It has a broad floor and steep sides

A U-shaped valley develops when a moving glacier occupies and abrades a pre-existing valley. The ice erodes both the floor and sides, widening and deepening it into a broad trough with steep, relatively straight walls. A river usually concentrates erosion in its channel and produces a narrower V-shaped valley. Hence option C is correct; the other choices describe neither glacial valley form nor its origin.

Correct answer: A. A broad flat-topped mesa may become a smaller isolated butte after further erosion

The correct answer is A. In a dry region of horizontally layered rocks, a resistant cap rock protects the softer beds beneath it. The remaining broad, flat-topped plateau is a mesa. As erosion narrows and isolates the protected remnant, it may become a smaller butte. A butte is therefore not a marine spit, a glacial valley, or a karst cave deposit, making B, C, and D incorrect.

Correct answer: A. Gradient, sediment load and discharge

Correct answer: A. A river channel pattern develops from the interaction of water energy, channel slope, sediment supply, bank strength, and discharge. Gradient affects potential energy and often influences velocity. Discharge affects the amount of water and the ability to erode and transport material. Sediment load, especially its amount and grain size, influences whether bars build and whether a channel becomes braided, while bank cohesion helps determine whether a river migrates in meanders. A is correct because it names three direct controls. B, C, and D contain features that do not provide the principal physical controls on ordinary channel pattern. A useful memory cue is E-S-D: energy from slope, sediment supply, and discharge.

Correct answer: B. Low gradient, steady discharge and finer sediment

Correct answer: B. Meanders are sinuous bends that commonly develop where a river can erode its outer bank and deposit sediment on its inner bank over time. A relatively low gradient, fairly steady discharge, and finer or more cohesive material can support this lateral migration. Braided channels are more often associated with abundant coarse sediment, variable discharge, multiple unstable bars, and frequently a larger sediment supply than one channel can carry. Therefore A generally favours braiding, not meandering. C describes a glacial setting, and D describes karst weathering; neither controls the normal choice here. The memory cue is: stable flow plus one shifting channel favours meanders; excess coarse sediment plus unstable bars favours braiding.

Correct answer: D. Gradual deposition during meander migration

Correct answer: D. A point bar forms on the inner side of a meander bend, where flow is slower and sediment is deposited. As the bar grows or as individual floods lose energy, larger and heavier grains tend to settle before smaller, lighter grains. A vertical succession that becomes finer upward can therefore record progressive deposition under decreasing or changing flow energy. During meander migration, the inner bank receives deposition while the outer bank is eroded, so D is correct. A is a coastal process involving a rock stack, B is erosion by moving glacier ice, and C is a karst mass-movement process. None explains point-bar sedimentation. Memory cue: inner bend builds, outer bend cuts; point bars commonly become finer upward.

Correct answer: A. Because it has little water vapour and weak vertical air movement

A is correct. Ordinary rain-forming clouds need moisture and rising air that cools and allows water vapour to condense. The stratosphere is very dry and comparatively stable, with little vertical mixing, so ordinary rainfall is uncommon there.

Correct answer: A. Temperature generally increases with altitude, which suppresses convection

A is correct. In much of the stratosphere, ozone absorbs ultraviolet radiation and temperature generally increases with altitude. This temperature pattern discourages air from continuing to rise, so vertical convection and mixing are weaker than in the troposphere. Most atmospheric water vapour and ordinary cloud formation are found in the troposphere.