2.  Chemical weathering involving rainwater and some minerals in rocks (feldspar + ferromagnesian)  React with feldspar and mica to form clay that crumbles easily and washed away  Clay are soft and expands in volume; causing granular disintegration  Iron in mica oxidised to form reddish-brown iron oxide  Resistant minerals like quartz are left unaltered and remain as sand  Reason why sedimentary rocks are formed by quartz and clay  Common in hot, wet regions

3. Spherodial weathering

4.  Swelling of rock minerals when they absorb water  Swelling causes stress in rocks, forcing grains apart  Anhydrous calcium sulphate absorbs water to form hydrated calcium sulphate (gypsum)  Repeated wetting and drying of minerals led to flaking of rocks; granular disintegration  Reversible change as mineral composition remains unchanged

6. Source: Interactive Geography Sec 3 textbook